US 10718642

I'll search for authoritative information on this specific patent number.

Let me run a couple more targeted checks to confirm front-page data and any litigation.

Summary — US 10,718,642 B2

Verification note: I confirmed this number via the Google Patents full text you supplied plus secondary sources (Justia, FreePatentsOnline, EPO/Global Dossier family data). No similar number was substituted. All identifiers below are reproduced literally.

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Bibliographic data

Abstract (verbatim): A method for checking an operability of two-wire measuring transducers in automation technology which output a measurement signal as an impressed loop direct current via a two-wire line and active assemblies of which are supplied with electrical energy via the two-wire line includes: measuring the loop direct current and an input voltage of the measuring transducer; increasing the loop direct current in a range from a minimum value to a maximum value independently of the measured value, while measuring the input voltage of the measuring transducer; storing the measured values of the input voltage at selected measuring points of the loop direct current as an individual signature of the measuring transducer; and, during ongoing operation, measuring the input voltage at connection terminals of the two-wire line via an internal resistance of the measuring transducer at a prevailing loop direct current and recursively comparing that with the signature.

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Plain-language overview of the independent claim

There is only one independent claim — claim 1. It is a method claim with five steps:

1. Measure the loop direct current (I_S) and the transmitter's input voltage (U_E).
2. Deliberately sweep the loop current from a minimum value to a maximum value independently of the measured process value, recording the input voltage as the current is varied. (In other words: a characterisation sweep not tied to the actual process measurement.)
3. Store the recorded input-voltage values at the selected loop-current test points as an "individual signature" of the two-wire measuring transducer — a per-device/per-loop fingerprint of how terminal voltage behaves versus loop current.
4. In normal ongoing operation, at whatever loop current happens to be flowing, measure the input voltage at the two-wire line's connection terminals (through the transducer's internal resistance) and recursively compare it against the signature at the same loop current. The word "recursively" here means the comparison is repeated on an ongoing basis.
5. Trigger a predefined reaction as soon as the measured input voltage deviates beyond a predefined tolerance from the signature at the prevailing loop current.

Dependent claims (2–7), briefly:

• 2 — Derive the voltage reserve (U_ER) from the signature as the difference between the input voltage at maximum loop current and the transmitter's required minimum input voltage (U_EM).
• 3 — Make the predefined tolerance proportional to that voltage reserve.
• 4 — Measure input voltage at two extreme loop currents and interpolate the remaining (current, voltage) tuples.
• 5 — Store the interpolated tuples as a table.
• 6 — Instead compute coefficients of an equation system from the measured tuples and store those as the signature.
• 7 — Place the two extreme loop currents outside the range of the measuring current I_M.

Practical effect: the transmitter can detect a creeping increase in loop/line/contact resistance (e.g., corrosion at terminals) during normal operation, without having to periodically force the whole 4–20 mA range and without having to "passivate" the host evaluation unit while doing so. A detected out-of-tolerance condition can be signalled as an out-of-range "fault current" (e.g., outside 4–20 mA) and/or reported via a DC-compensated AC signal (FSK/HART).

Notable drafting point (uncertainty flag): the granted claim 1 refers to the signature as being "of the two-wire measuring transducer," whereas the specification repeatedly describes it as "an individual signature of the current loop with the measuring transducer." The two formulations are not identical in scope. Separately, claim 1's final clause ("leaves a predefined tolerance via the internal resistance …") is grammatically awkward/possibly truncated in the published text; the specification counterpart reads "leaves a predefined tolerance." I flag these as literal-text observations, not corrections.

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Litigation / CAFC 2026 docket search

I found no results connecting US 10,718,642 to any Court of Appeals for the Federal Circuit 2026 docket, or to any district-court or PTAB proceeding. Searches of federal-circuit opinion/order materials for that number returned unrelated 2026 cases (e.g., CogniPower v. Samsung, 2026-1559; In re BadgeCert, 2026-1000; an Exafer v. Microsoft rehearing petition; several PTAB Fintiv-style discretionary-denial papers involving other patents). The patent's own record shows only prosecution events (a non-final office action in 2019, response, grant) and maintenance-fee payments.

Uncertainty statement: I cannot certify a true absence of litigation or a CAFC appeal. My search coverage is web-indexed sources (Google Patents, Justia, FreePatentsOnline, cafc.uscourts.gov PDFs, PTAB petition pages), not a direct PACER, CAFC docket, or USPTO PatentCenter query. A negative web result is weak evidence of no case; a live PACER/CAFC docket lookup would be required to confirm. If you need a definitive litigation history, that is the authoritative step I could not perform here.

I'll run targeted searches across patent-litigation sources for this specific number. Building on the prior negative finding, I'll try to confirm or overturn it.

Let me try more direct litigation-database queries for this specific number.

Litigation search — US 10,718,642 B2

Result: No litigation found.

I searched patent-litigation aggregators and court-opinion sources for the specific number 10718642 (and the variants 10,718,642 / 10/718,642). I found no district-court action, ITC investigation, PTAB post-grant proceeding, or Federal Circuit appeal involving this patent.

What was searched and what came back

Important false positive to flag

One result returned the bare digit-string 10718642 — but it was a UK Companies House registration number for a company ("ASDERON LTD", appearing in a London Gazette dissolution/filing list, entry ASDERON LTD 10718642 29/03/2022). This is a coincidental numeric match, not US patent 10,718,642 and not litigation. Per the operating rule to interpret identifiers literally and not conflate similar numbers, I am not treating this as a hit and am not rendering it as 10,718,642.

Case-by-case table

Because no suits were located, there are no plaintiff/defendant/jurisdiction/case-number/filing-date/outcome entries to populate:

Consistency with the prior section

This confirms and extends the earlier-generated "Litigation / CAFC 2026 docket search" section, which likewise found no proceedings. No contradiction to flag; the two are consistent.

Confidence and limitations (stated explicitly)

• I cannot certify a true absence of litigation. My coverage is web-indexed sources (Google Patents family data, Unified Patents portal results, CAFC opinion PDFs, PTAB petition pages, general news/aggregator pages) — not a direct PACER query, not the CAFC's own docket system, and not USPTO PatentCenter. A negative web result is weak evidence of no case.
• Two of my targeted queries (docketalarm, the ABB/Schwanzer caption search) did not complete because the tool-run hit its step limit. So Docket Alarm, Justia Dockets, and CourtListener were not fully queried for this number in this pass.
• The patent's own front page shows only prosecution and maintenance-fee events (2019 non-final office action, response, 2020-07-21 grant; 4th-year maintenance fee paid 2024-01-11) — no reexamination, IPR, or litigation certificate entries.

To obtain a definitive litigation history, the authoritative next steps would be: (1) a direct PACER Case Locator query for 10718642; (2) the CAFC's own docket search; and (3) USPTO PatentCenter / PTAB API query. Those are lookups I could not perform here. Based on all available web-indexed evidence, however, no litigation is known involving US 10,718,642.

I'll verify the structured PTAB data against live sources before reporting.

The first two searches returned nothing relevant. Let me run a few more targeted checks to be thorough before concluding.

Let me run a final round of checks against PTAB docket aggregators and the specific patent title.

Proceedings overview

Total AIA trial proceedings on file for US 10,718,642: zero (0). The structured "PTAB proceedings on file" block — sourced from the USPTO Open Data Portal — returns no IPR, PGR, or CBM proceedings, so the status breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials. The defensive posture this gives a defendant is adverse: the patent is entirely untested at the Board, all seven claims (including independent claim 1) stand unamended and unchallenged, and there is no estoppel or FWD on which a defendant can free-ride. Conversely, there is also no adverse PTAB record to clear — a first-filer gets a clean slate on art selection and no § 325(d) "second bite" exposure.

My independent web checks (Google Patents, PTAB E2E / PTACTS petition documents, Justia, FPO, EPO family data, and general docket aggregators) surfaced no petition, institution decision, FWD, or appeal naming US 10,718,642. Every "10,718,642" hit was either an unrelated patent number ('642 patents in other families), a UK Companies House registration number, or a false-positive string match. Searches for the patent title plus "IPR/petition," and for assignee "ABB Schweiz" together with the inventors, returned nothing.

Proceedings list

None to enumerate. There is no proceeding number to report, and I will not invent one. Per the canonical structured block, no AIA trial has ever been filed against this patent as of the most recent ODP ingest.

For completeness, the patent's entire public post-grant record is prosecution-side only, as reflected in the front-page data already generated:

No reexamination, no derivation, no interference, no AIA trial. Consistent with that, my earlier litigation sweep (in the prior section) also found no district-court or Federal Circuit activity connecting this patent to any 2026 CAFC docket.

Strategic summary

Claim status. All claims 1–7 are UNTESTED at the PTAB. None is canceled, none has been narrowed by certificate of correction or reissue, and — importantly — no claim has been confirmed by the Board either. There is no statutory disclaimer and no IPR-issued amendment. So a defendant asserting invalidity in litigation faces the full original claim set with the ordinary Rule 282 presumption of validity intact, and no PTAB ruling to cite for or against.

Estoppel landscape. § 315(e)(2) estoppel is empty. Because no IPR/PGR was ever instituted and no FWD ever issued, no petitioner, RPI, or privy is barred from raising any § 102/§ 103 ground before the PTAB. Any accused infringer today is free to file a first IPR on any patent-or-printed-publication basis. Two procedural cautions: (i) the patent's priority date is 2016-09-01 and it issued 2020-07-21, so the § 315(b) one-year bar runs from service of a complaint on you — watch that clock; (ii) General Plastic "follow-on petition" risk does not attach to the patent yet, but it will attach to your own first filing if you split grounds across petitions, so front-load the art.

Art landscape — where a challenger should look. The prosecution-file and family-citation record already generated points to the substantive battleground:

• DE 10 2005 047 894 A1 (ABB Patent GmbH, 2007-04-19) — cited on the face of the patent and discussed adversely in the specification as the closest prior approach ("transmitter test method … emits a test signal as a load-independent loop co-current via a two-wire lead"). The patent distinguishes it on the ground that the prior method requires periodically sweeping the entire current range independently of the measured value and synchronizing with the host. A petitioner must show that teaching the sweep plus storing/compare logic was obvious; expect the patentee to lean hard on this file-wrapper distinction.
• US 7,358,744 B2, "Method for testing the serviceability of transducers," and US 10,367,612 B2 (Rosemount, "Process variable transmitter with self-learning loop diagnostics") appear respectively in "Similar Documents" and "Family Cites Families." The latter is a self-learning loop-diagnostics patent — conceptually adjacent to the "individual signature … recursively compared" core of claim 1 — and is the most promising non-DE starting reference to develop, particularly for a § 103 combination attacking the learning/storing-then-comparing limitations.
• US 5,481,200 / DE 69429008 T2 (Rosemount "built-in test equipment") and DE 10 2007 062 919 A1 (Endress+Hauser, loop-current/voltage-drop diagnosis) round out the field.

Pattern signals. No petitioner has ever filed, so there is no serial-filer pattern and no defensive aggregator (Unified Patents, RPX, et al.) visible in the chain. The patent owner — ABB Schweiz AG, a large-entity operating company, not an NPE — has never had to defend at the Board, so it has no proven PTAB litigation posture and no established panel experience. The family is comparatively live: EP3507573B1, CN109690258B, DE102016116378B4, WO2018041968A1 are all in force. That matters because a concurrent EPO opposition or appeal against EP3507573B1 would generate useful counterpart construction and prior-art analysis — I did not confirm whether EP3507573B1 is under opposition (the one EPO Board of Appeal decision my search returned, T 2106/95-adjacent materials, concerned a different patent about azimuthing marine propulsion, not this family). Treat that as an open, high-value lead rather than a verified fact.

Recommended next steps

1. If you are a defendant or prospective petitioner — file, don't wait. This is the rare case where the patent has never been challenged. A well-built first IPR naming DE 10 2005 047 894 A1 as primary, combined with a self-learning-diagnostics reference (start with US 10,367,612) and US 7,358,744, is not subject to any estoppel, § 325(d) overlap, or General Plastic handicap. Calendar the § 315(b) one-year bar from your complaint service date and the § 315(a)(1) civil-action bar if you are also litigating.
2. Attack claim 1 with precision on "independently of the measured value" and "recursively." These are the load-bearing limitations that distinguish the specification over DE '894. A petition that treats the sweep + storage + runtime comparison as a generic monitoring step invites a Patent Owner argument that the prior art required host passivation — the very problem the patent claims to solve. Build a § 103 rationale that expressly addresses that "passivation/synchronization" motivation gap.
3. Verify the foreign track. Confirm whether EP3507573B1 is under EPO opposition or appeal and pull any written decision — foreign prosecution/opposition reasoning on the same claims is the cheapest way to identify strong art. I could not confirm this from web sources.
4. Watch for the first filing. Because well-asserted patents reliably attract IPRs, the absence today is best read as "not yet asserted," not "unassailable." If ABB begins asserting US 10,718,642, expect the first petition within one year of the earliest complaint.
5. Do not cite an FWD. There isn't one. If any demand letter or invalidity contentions you receive purport to rely on a PTAB outcome for this patent, that assertion is fabricated — no proceeding exists.

Uncertainty statement (unchanged in kind from the prior section): the definitive authority is USPTO PatentCenter / PTAB E2E and PACER, which I could not query directly. The structured ODP block is my canonical source and it is empty; my web corroboration is also negative. A negative web result is weak evidence of true absence, though here it is reinforced by the structured data. Note the limits of scope too: even a verified "no AIA trial" does not rule out ex parte reexamination (which is not an AIA trial and does not appear in the trial-proceeding block) or foreign challenges — those would require separate PatentCenter and EPO Register lookups I did not perform.

I'll research the assignment record and ownership chain for US 10,718,642.

Ownership & Assignment Analysis — US 10,718,642 B2

Critical sourcing caveat up front: The authoritative Assignment Center / Patent Assignment Search detail pages (assignmentcenter.uspto.gov, assignment.uspto.gov) were not retrievable in my searches for this patent number, and I could not pull the full reel-051462/0022 cover sheet. What I can state with confidence is what the granted patent front page and Google Patents legal-events record literally disclose. I flag exactly where I am inferring versus quoting. I did not find (and therefore do not report) any post-issuance assignment.

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Inventors

Basis: Both names appear together as inventors on other ABB Schweiz AG German patents, e.g. DE 10 2015 000 728 B4 (Schwanzer, Merlin + others) and DE 10 2017 111 242 B4 (Schwanzer, Merlin + others), all assigned to ABB Schweiz AG. This is a consistent pattern of long-tenure ABB measurement/analytics inventors at ABB's German operations, not a founder-team that later cashes out.

• Departure pattern: No evidence — from these sources — that either inventor departed ABB within 12 months of filing. I cannot positively confirm continued employment (that would require employment/linkedin-type sources I did not exhaust), so treat "no departure signal" as absence of evidence, not proof.
• Unusual-pattern check: None detected. Two-inventor, single-employer, standard corporate invention.

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Original assignee

ABB Schweiz AG — Bruggerstrasse/Brown Boveri Strasse, 5400 Baden, Switzerland.

• Named on the issued patent? Yes. Google Patents lists "Original Assignee: ABB Schweiz AG" and "Current Assignee: ABB Schweiz AG."
• Primary line of business / product embodiment: ABB is a global electrification, automation and digitalization group. ABB Schweiz AG is the group's principal Swiss operating/IP entity. This patent (two-wire process measuring transducers / field transmitters, 4–20 mA loop) sits squarely inside ABB's measurement & analytics product line (field instruments for process automation) — a real, shipped product category (e.g., pressure/temperature transmitters), so there is a plausible commercial embodiment. Note: I did not identify a specific ABB catalog model that reads on the claims; that is an assertion I am not making.
• Current status: Operating. No bankruptcy, dissolution, or fire-sale indicator found. (Separately, ABB divested its Power Grids division to Hitachi in 2020, but that business is distinct from the measurement/analytics subject matter here, and the Patent Office record was not updated to reflect any transfer of this patent.)

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Assignment timeline

Chronological record as reflected by the patent front page + Google Patents legal events:

• 2019-03-08 → 2019-03-12 (executed) / recorded 2020-01-09 — Reel 051462/0022
  • Conveyance: Assignment
  • Assignor: Schwanzer, Horst; Merlin, Tilo
  • Assignee: ABB Schweiz AG, Switzerland
  • Correspondent: Not retrieved. The legal-events entry names only assignors/assignee and the reel/frame ("ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SCHWANZER, HORST;MERLIN, TILO;SIGNING DATES FROM 20190308 TO 20190312;REEL/FRAME:051462/0022"). I could not surface the correspondent attorney-of-record field from the Assignment Center cover sheet, so I will not name one. (For the related German family work, the recorded representative is ABB Patent GmbH, 40472 Ratingen, DE — e.g., on DE 10 2015 000 728 B4 — and Maiwald GmbH, Düsseldorf on DE 10 2017 111 242 B4. Those are DE-side representatives, not evidence of the US recording correspondent.)
  • Context: Standard inventor-to-original-assignee (employment) assignment — executed ~3 weeks after the DE priority filing and shortly after the PCT filing; routine corporate ownership capture, not a fire-sale or reorg.

No other assignments are recorded. The remaining Google Patents legal events are prosecution and fee events only, not conveyances:

• 2020-02-28 — Petition related to maintenance fees granted (fee administration, not a transfer)
• 2020-06-10 / 2020-06-30 — issue-fee / patent-grant events
• 2024-01-11 — payment of 4th-year maintenance fee (large entity)

Finding: The only recorded conveyance is the initial inventor→ABB assignment. There is no post-issuance assignment, security interest, merger, or change-of-name on record. This generally means the original assignee still owns the patent, consistent with the "Current Assignee: ABB Schweiz AG" listing.

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Timeline diagram

timeline
    title Ownership of US 10718642
    2016 : DE priority patent filed
    2017 : PCT application filed
    2019 : Inventors assign rights to ABB Schweiz AG
         : US application filed as continuation
    2020 : US patent granted
    2024 : Year 4 maintenance fee paid

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NPE / troll-pattern signals

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Verdict

Insufficient data — specifically, only the original assignment is on record.

Justification: The entire recorded chain is a single inventor-to-assignee conveyance — Reel 051462/0022, executed 2019-03-08/12, recorded 2020-01-09 — from Schwanzer and Merlin to ABB Schweiz AG, the operating company that still appears as current assignee. There is no sale, no licensing entity, no cascading LLC chain, and no litigation, so none of the assertion-enabling signals (1–8) fire. Because the chain terminates at its original operating-company owner with no post-issuance activity, the honest classification is insufficient data / original assignee retains ownership, not an NPE finding.

Caveat on completeness: I could not open the Assignment Center cover sheet for Reel 051462/0022 to read the recorded correspondent field, and my litigation/assignment coverage is web-indexed (Google Patents, JPO/EPO family data, FreePatentsOnline) rather than a direct assignmentcenter.uspto.gov or PACER query. If a later assignment exists that is not yet reflected on the Google Patents legal-events tab, I would not have surfaced it.

Verify at: https://assignmentcenter.uspto.gov/ (search "10718642" or Reel/Frame 051462/0022) and https://assignment.uspto.gov/patent/index.html.

I'll verify the patent on USPTO-facing sources and then dig into each cited reference. Let me run several searches in parallel.

Good grounding so far. Let me pull the remaining cited references, especially the Schölz US counterpart and the other family citations.

I hit the tool-step limit before I could retrieve independent detail on a few of the more minor citations, so I've flagged confidence levels explicitly where that's the case. Here is the analysis.

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Prior-art analysis — US 10,718,642 B2

0. Patent verification (USPTO-facing sources)

I did not substitute a similar number. Web-indexed corroboration: Justia (https://patents.justia.com/patent/10718642), FreePatentsOnline pre-grant pub (https://www.freepatentsonline.com/y2019/0195667.html), Google Patents (https://patents.google.com/patent/US10718642/en), EPO register family (EP3507573A1, CN109690258, DE102016116378).

Caveat on "USPTO database": the sources I could reach are web-indexed mirrors of USPTO/EPO data, not a direct PatentCenter API query. The bibliographic identity is solid; treat this as strong, but not a native-PatentCenter certification.

Legal framework for the § 102 discussion

• Effective filing date / priority: 2016-09-01 → AIA applies (post-16 March 2013).
• Every examiner citation below published years before 2016-09-01, so each is available as prior art under § 102(a)(1) (patented / printed publication before the effective filing date).
• US 10,367,612 B2 is the one exception to check carefully: it has an effective filing date of 2015-09-30 (before the '642 priority) but a grant/publication date after — so it is potentially § 102(a)(2) art, not (a)(1) art.

Important framing: the nine examiner citations are a narrow set. As shown below, none of them alone anticipates claim 1, because claim 1 requires the combination of (i) a per-device "individual signature" recording step and (ii) a recursive comparison against that stored signature during normal operation at the prevailing loop current. Most citations supply only the current-sweep + voltage-measure sub-steps in a test-mode context. They are properly characterized as § 103 combination art, with one true § 102 reference for individual sub-elements.

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1. Examiner citations (the 9 "Citations" on the face of the patent)

1.1 US 5,481,200 A — Field transmitter built-in test equipment

• Citation: US 5,481,200 A; appl. US 08/121,064; filed 1993-09-15; granted 1996-01-02; inventor Voegele et al.; assignee Rosemount Inc. (face of patent reads "Rosemont Inc.").
• Description: A 4–20 mA field transmitter with built-in test circuitry. Per the family equivalent CA 2169722 A1, the test routine sets the loop current through the two-wire circuit to a second current level (i.e., forces a non-measurement loop current) and checks a response — an on-board self-test that perturbs the loop independent of the process variable.
• § 102/§ 103 relevance: Bears on the "increasing the impressed loop direct current … independently of the measured value, while measuring …" concept and on field-transmitter self-test generally. Does not disclose storing voltage-vs-current as a signature, nor recursive comparison at the prevailing loop current. Best read as § 103 art feeding the "sweep the loop and observe" motivation; not a standalone § 102 anticipation of claim 1.
• Source: https://patents.google.com/patent/CA2169722A1

1.2 DE 299 17 651 U1 — Transmitter and process control system (Messumformer und Prozessleitsystem)

• Citation: DE 299 17 651 U1; filed 1999-10-07; published 2000-11-09; assignee Siemens AG.
• Description: German utility model directed to a transmitter and associated process control system.
• § 102 relevance: General two-wire transmitter / loop architecture background. Low confidence on specifics — I could not retrieve the full text within the tool budget. Treat as peripheral § 103/background art pending full-text review.

1.3 US 2002/0145528 A1 — Electrical transducer

• Citation: US 2002/0145528 A1; filed 2001-01-22; published 2002-10-10; assignee ifm electronic gmbh.
• Description: An electrical transducer (field-device/sensor front-end) application.
• § 102 relevance: Background art for field-transducer architecture. Low confidence on specifics — not retrieved in full. Included by the examiner, but on its title/field it does not appear to disclose the signature/recursive-comparison core.

1.4 DE 10 2005 047 894 A1 — Testing method… (and its US counterparts US 7,358,744 B2 / US 2007/0108925 A1)

• Citation (family): DE 10 2005 047 894 A1, filed 2005-10-06, published 2007-04-19, ABB Patent GmbH; US 7,358,744 B2, granted 2008-04-15 (pub. US 2007/0108925 A1, 2007-05-17), inventor Wolfgang Scholz, assignee ABB Patent GmbH.
• Description: This is the single most material reference. It discloses: increasing the DC loop current, independently of the measurement signal, from a minimum toward a maximum I_SM; measuring the input voltage U_E across the internal resistance of the transducer in the process; comparing U_E to a definable threshold U_ES that is greater than the minimum input voltage U_EM; and, if U_E falls below the threshold before I_S reaches maximum, reducing the loop current and signalling a fault. It uses FIG. 2 characteristic curves 401/402, U_EM, I_SM, I_SG — the identical figure/numeral scheme reused in US 10,718,642.
• § 102 relevance — the key finding: On the pre-characterisation/sweep step of claim 1, this reference is a strong § 102(a)(1) anticipation candidate in isolation. Notably, US 10,718,642's own Background expressly identifies DE 10 2005 047 894 A1 as prior art and states its disadvantage (needing to sweep the full current range and passivate the host), which is precisely what claim 1 is drafted to avoid. However, for claim 1 as a whole it does not anticipate, because it compares against a fixed threshold U_ES, not a stored individual signature, and it does not perform the recursive comparison at the prevailing (arbitrary) loop current during ongoing operation. It also lacks the claimed triggering of a predefined reaction as soon as the input voltage leaves a predefined tolerance vs. the signature (it reacts to a fixed setpoint). So: § 102 for the sweep-and-measure sub-steps; § 103 for the claim as a whole.
• Sources: https://patents.google.com/patent/DE102005047894A1/en; https://patents.google.com/patent/US7358744

1.5 US 2008/0013226 A1 — External electrical energy supply for field device

• Citation: US 2008/0013226 A1; filed 2006-07-13; published 2008-01-17; assignee Endress + Hauser Flowtec AG.
• Description: External energy supply for a two-wire field device (loop-powering architecture).
• § 102 relevance: Background on the two-wire power/energy-supply context that claim 1 presupposes. Low-to-moderate confidence; not retrieved in full. Does not appear to reach the signature/comparison features.

1.6 US 2009/0110039 A1 — Bus interface unit for interposing in a two-wire current loop…

• Citation: US 2009/0110039 A1; filed 2007-10-22; published 2009-04-30; inventor Valentin Kort.
• Description: A bus interface unit interposable in a two-wire current loop, plus a transducer, position controller and analog I/O module using it — i.e., a loop-side interface for measuring/conditioning loop current.
• § 102 relevance: Bears on the general technique of sensing loop current over a measuring resistor in a two-wire loop (the U_M measurement underlying "measuring the impressed loop direct current"). Background/§ 103 only. Moderate confidence (title + abstract level).

1.7 US 2009/0117873 A1 — Electric device

• Citation: US 2009/0117873 A1; filed 2007-10-01; published 2009-05-07; inventor Edson Leocadio Ferreira.
• Description: A generic electric device in the field-device/loop-measurement space.
• § 102 relevance: Low; general background. Low confidence on specifics (not retrieved).

1.8 DE 10 2007 062 919 A1 — Device for diagnosing or determining operating conditions or environmental conditions of a field device…

• Citation: DE 10 2007 062 919 A1; filed 2007-12-21; published 2009-06-25; assignee Endress + Hauser GmbH + Co. KG.
• Description: A field device diagnostic apparatus having a first voltage-measuring unit that determines the actual loop current I_S from the voltage drop across an internal measuring resistor, a second unit that measures the actual burden voltage, and an evaluation/display unit that shows these as operating conditions.
• § 102 relevance: Directly relevant to two sub-steps of claim 1: measuring the loop current (via internal measuring-resistor drop) and measuring an operating voltage condition. It does not disclose a stored per-device signature nor recursive comparison at the prevailing loop current, and it is a display/diagnostic teaching. § 103 art for the loop-current and voltage-measurement steps; not § 102 for claim 1.
• Source: https://patentimages.storage.googleapis.com/53/b5/72/f44f8146ffdefc/DE102007062919A1.pdf

1.9 US 2014/0363031 A1 — Analog Input Module

• Citation: US 2014/0363031 A1; filed 2013-06-11; published 2014-12-11; assignee Siemens AG.
• Description: Analog input module (the control-room-side counterpart that reads the 4–20 mA loop and detects out-of-range/fault currents).
• § 102 relevance: Relevant to the "fault current outside the 4–20 mA measuring range" reaction used in the spec (not claim 1's trigger itself). Background/§ 103. Low-to-moderate confidence on specifics.

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2. Family/other citations ("Family Cites Families" — 11 references)

These were cited during related-family prosecution and matter because two of them are closer to the claimed concept than anything on the examiner list.

2.1 US 10,367,612 B2 — Process variable transmitter with self-learning loop diagnostics

• Citation: US 10,367,612 B2; priority 2015-09-30; granted 2019-07-30; assignee Rosemount Inc.
• Description: A process-variable transmitter that performs self-learning loop diagnostics — it learns a baseline behaviour of the loop and later detects deviations from it. Conceptually this is the closest match to the "store a signature, then compare against it during operation" idea of claim 1.
• § 102 relevance — flagged as the most important reference to reconcile: Because its effective filing (2015-09-30) predates the '642 priority (2016-09-01), it is a genuine § 102(a)(2) candidate. The critical open question — which I cannot resolve from the retrieved material — is what is learned/compared and whether it is the input/terminal voltage vs. loop current across a swept range at the prevailing loop current. If Rosemount's self-learning diagnostic learns a loop signature and compares it recursively at the prevailing loop current, it would be a serious § 102(a)(2) anticipation of claim 1. This reference deserves a dedicated full-text and prosecution-history comparison.
• Source: Google Patents related-documents listing under US10718642.

2.2 DE 102006030774 A1 — Method for determining the load resistance for a transmitter

• Citation: DE 10 2006 030 774 A1; filed 2006-06-30; published 2008-02-21; assignee Endress + Hauser Conducta.
• Description: Determining a transmitter's load/loop resistance — i.e., the same quantity the '642 spec derives ("the loop resistance of the two-wire line is calculated from the input voltage and the loop direct current").
• § 102 relevance: Strong on the loop-resistance-determination sub-concept; relevant to the specification's loop-resistance calculation. § 103 art; not retrieved in full, moderate confidence.

2.3 RU 2 490 596 C1 — Process parameter transducer with two-wire process control diagnostics

• Citation: RU 2 490 596 C1; filed 2009-07-09; granted 2013-08-20; assignee Rosemount Inc.
• Description: Two-wire process-control diagnostics in a process-parameter transmitter (the family of Rosemount's loop-diagnostic line of art).
• § 102 relevance: Background on loop diagnostics; relevant to the general motivation for in-operation diagnostics. Moderate confidence.

2.4 EP 2 219 013 B1 — Energy production device for producing and simultaneously monitoring measured current

• Citation: EP 2 219 013 B1; filed 2009-02-13; granted 2019-04-10; assignee VEGA Grieshaber KG.
• Description: Producing loop energy while simultaneously monitoring the measured loop current in a two-wire device.
• § 102 relevance: Relates to monitoring loop current during operation (the "ongoing operation" measurement). Background/§ 103. Moderate confidence.

2.5 DE 10 2011 082 018 A1 — Method for operating a field instrument…

• Citation: DE 10 2011 082 018 A1; filed 2011-09-01; published 2013-03-07; assignee Siemens AG.
• Description: Operating method for a process-instrumentation field device. Low-to-moderate confidence on specifics (not retrieved).

2.6 DE 697 14 606 T9 — Rosemount Inc. — Device for checking a control signal coming from a plant in a process control

• Citation: DE 697 14 606 T9 (translation of a 1996-declared priority family); priority 1996-12-31; assignee Rosemount Inc.
• § 102 relevance: Early process-control loop-signal checking. Background. Low confidence on specifics.

2.7 US 7,719,812 B2 — Astec International Limited — Power converters with rate of change monitoring for fault prediction and/or detection

• Citation: US 7,719,812 B2; filed 2007-05-15; granted 2010-05-18.
• § 102 relevance: "Rate-of-change monitoring for fault prediction" is analogous to the diagnostic philosophy (trend detection before failure) but is in power-converter art, not two-wire loop diagnostics. § 103 / analogous-art only.

2.8 JP 2008-295265 A — Tamagawa Seiki Co Ltd — Overcurrent detection circuit

• Citation: JP 2008-295265 A; filed/published 2007-05-28 / 2008-12-04.
• § 102 relevance: Overcurrent detection — peripheral. § 103.

2.9 EP 2 156 200 B1 — ABB Technology AG — Increased reliability in the processing of digital signals

• Citation: EP 2 156 200 B1; filed 2007-06-07; granted 2016-03-23.
• § 102 relevance: Same-assignee (ABB) reliability-in-digital-signal-processing art; background. § 103.

2.10 CN 101494412 B — Error detection device and detection method for power converter

• Citation: CN 101494412 B; filed 2008-01-24; granted 2012-08-22.
• § 102 relevance: Power-converter error detection; distant art. § 103/background.

2.11 ES 2378616 T3 — ABB Research Ltd. — Apparatus and procedure for controlling a transmission line

• Citation: ES 2378616 T3; filed 2008-04-18; granted 2012-04-16.
• § 102 relevance: Transmission-line control apparatus (same-assignee ABB). Background. Low confidence.

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3. Consolidated § 102 / § 103 assessment

Bottom line

1. No single examiner citation anticipates claim 1. The two-part core of claim 1 — (i) storing the input-voltage-vs-loop-current relationship as an individual signature and (ii) recursively comparing against it at the prevailing loop current during ongoing operation — is not disclosed by any of the nine examiner citations. At most they collectively render obvious the sweep-and-measure preamble, so they are § 103 art.
2. DE 10 2005 047 894 A1 (US 7,358,744 B2) is the strongest single reference and is the closest to a § 102 print against the sweep/measure sub-steps; US 10,718,642's own Background section distinguishes over it, which is likely how claim 1 was allowed.
3. US 10,367,612 B2 (Rosemount, self-learning loop diagnostics) is the one reference I would escalate. It is not on the examiner citation list but appears in the family citations, it qualifies as § 102(a)(2) art on timing (effective filing 2015-09-30 < 2016-09-01), and its "self-learning + compare-to-learned-baseline" concept is the nearest conceptual match to claim 1. Whether it actually discloses the input/terminal voltage vs. loop current signature and the recursive-at-prevailing-current comparison must be checked in its full text and its specification before any § 102 conclusion is drawn.

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4. Confidence and limitations (explicit)

• Verified with retrieved text: US 5,481,200 (via CA 2169722), DE 10 2005 047 894 A1 / US 7,358,744 B2 / US 2007/0108925 A1, DE 10 2007 062 919 A1.
• Identified by title/abstract only (lower confidence on the specific disclosures): DE 299 17 651 U1, US 2002/0145528 A1, US 2008/0013226 A1, US 2009/0110039 A1, US 2009/0117873 A1, US 2014/0363031 A1, DE 10 2006 030 774 A1, RU 2 490 596 C1, EP 2 219 013 B1, DE 10 2011 082 018 A1, US 10,367,612 B2, and the remaining family citations.
• I did not retrieve full claim charts, and I did not run a native USPTO PatentCenter/Global Dossier query (the tool budget was exhausted mid-run). A true anticipation opinion under § 102 requires the full text of each reference plus its prosecution history — particularly for US 10,367,612 B2.
• All dates above are reproduced literally from the sources; where the face of US 10,718,642 prints "Rosemont Inc." (for Rosemount) and "Wolfang Scholz" (for Wolfgang Scholz), I have preserved the patent's spelling and noted the discrepancy rather than auto-correcting it.

I'll ground this analysis with targeted searches on the key prior-art references listed on the patent.

Good — I now have strong grounding. Let me verify a few more listed references before drafting.

Obviousness Analysis — US 10,718,642 B2 under 35 U.S.C. § 103

Analysis date: 2026 (note: the task header states "April 26, 2026" while the session metadata states 2026-09-29; I flag this rather than silently pick one). This section builds on, and does not repeat, the previously generated Patent summary and Litigation summary sections.

Grounding note: I treat the Google Patents full text supplied in the user message as authoritative. Where I rely on search results for the content of a prior-art reference, I cite it. Where I only have the reference's title/face data from the patent page (because my tool-run hit its step limit before I could retrieve its text), I say so explicitly and do not assign it disclosure content.

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0. Threshold corrections and flags

1. Literal identifiers preserved. No reference number below has been auto-corrected. In particular, I keep DE 10 2005 047 894 A1, US 7,358,744 B2, and US 2007/0108925 A1 as distinct documents that are members of one family (Scholz / ABB Patent GmbH), and I keep US 10,367,612 B2, US 2017/0093533 A1, and WO 2017/058 527 A1 as distinct documents of another family (McCoy & Lauzon / Rosemount Inc.).
2. Build-on flag (no contradiction). The previously generated summary flagged that granted claim 1 recites the signature as being "of the two‑wire measuring transducer," whereas the specification says "an individual signature of the current loop with the measuring transducer." That discrepancy is material to § 103, and I address it at § 9 below. No contradiction with the prior section — only an extension.
3. Prosecution-art asymmetry (important). The US patent's own front page lists 9 "Citations" (examiner/third-party) and 11 "Family Cites Families." The German search report for family member DE 10 2016 116 378 B4 independently lists: DE 10 2005 047 894 A1; DE 10 2011 082 018 A1; DE 694 29 008 T2; DE 697 14 606 T9; US 9 182 256 B2; WO 2017/058 527 A1. Two of these — US 9,182,256 B2 and WO 2017/058 527 A1 — do not appear in the US "Citations" list but do appear in the family-citation list. That is the single most important structural fact for this § 103 analysis: a sibling-office examiner appears to have considered precisely the combination I set out below.

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1. Legal framework applied

• 35 U.S.C. § 103 (pre-AIA vs. AIA is not dispositive here; the US 16/288,125 application was filed 2019-02-28 as a continuation with a 2016-09-01 priority claim, so the AIA §§ 102/103 framework governs the priority claim, while the substance of Graham/KSR applies either way).
• Graham v. John Deere Co., 383 U.S. 1 (1966): scope and content of the prior art; differences between the prior art and the claims; level of ordinary skill; secondary considerations.
• KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007): a combination is obvious where the elements are known, the combination is of a finite number of predictable solutions, and there is an articulated reason with a reasonable expectation of success. "[A]ny need or problem known in the field of endeavor at the time of invention and addressed by the patent can provide a reason for combining the elements."
• In re Keller / In re Merck and MPEP 2143: a reference may be modified in view of another reference; predictability, not absolute certainty, is the standard.

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2. Level of ordinary skill in the art (PHOSITA)

A PHOSITA here is an engineer (B.S. electrical/process instrumentation or equivalent) with roughly 2–5 years of experience with industrial two‑wire (loop-powered) 4–20 mA/HART field transmitters, including loop power budgeting (terminal-voltage vs. loop-resistance vs. minimum operating voltage, U_E = U_B − I_S·(R_wire + R_sense)), and the basic diagnostics mathematics of curve fitting and threshold comparison. This is a mature, well-characterized art — a factor that favors obviousness. The patent's own specification confirms that all of the constituent techniques (sweeping loop current, measuring terminal voltage, fault-current signaling, FSK/HART parameter transmission, table/polynomial curve fitting) were conventional.

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3. The claimed subject matter — element decomposition of claim 1

Restating claim 1 as distinct limitations (cross-referencing, not repeating, the prior section's plain-language overview):

Dependent claims: 2 (voltage reserve U_ER = U_E@I_SM − U_EM); 3 (tolerance ∝ U_ER); 4 (measure at two extreme loop currents; interpolate remaining tuples); 5 (store interpolated tuples as a table); 6 (calculate and store coefficients of an equation system as the signature); 7 (the two extreme loop currents lie outside the range of the measuring current I_M).

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4. The prior-art references and what each discloses

4.1 Primary reference — DE 10 2005 047 894 A1 / US 7,358,744 B2 / US 2007/0108925 A1 (Scholz; ABB Patent GmbH) — the applicant's own admitted prior art

This is the reference the '642 specification itself identifies and criticizes. Verified content (Google Patents DE102005047894A1, and US7358744 claim 1, both retrieved):

• Preamble/L1: "two-wire transducers in automation engineering that output a measurement signal as an injected DC loop current via a two-wire line, and whose active components are supplied with electrical power via the same two-wire line."
• L2: measures the DC loop current I_S and the input voltage U_E across the internal resistance 110, 120 of the transducer.
• L3: "the DC loop current (I_S) is increased, independently of the measurement signal, from a minimum value towards a maximum value (I_SM), and an input voltage (U_E) … is measured in the process." The DE text adds that this may be "continuous or incremental," each step being held until the measured input voltage remains constant.
• L6-ish: compares U_E with a "definable threshold value (U_ES) that is greater than a minimum input voltage (U_EM) required to maintain serviceability," and if U_E falls below U_ES before I_S reaches I_SM, reduces I_S until U_E reaches at least U_ES and signals the error. It also uses a DC-compensated AC signal to report the condition.
• Express purpose: performed "during commissioning of the transducer or at every switch-on," and "alternatively … during the intended use … as needed," including "periodically."

What '894 does not disclose: L4 (storing the measured values as an individual signature), and L5 (recursive comparison against that signature during ongoing operation). '894 compares against a fixed, pre-set threshold U_ES, not against a device-specific stored curve, and it is fundamentally a periodic/commissioning sweep that requires "passivating" the host evaluation unit.

4.2 Secondary reference A — US 9,182,256 B2 (Wehrs, LeCuyer, Lo, McCoy, Westfield; Rosemount Inc.), "Process variable transmitter with two-wire process control loop diagnostics" — cited in the German search report

Verified from freepatentsonline.com/9182256.html:

• Two-wire process variable transmitter with loop current measurement circuitry and terminal voltage measurement circuitry measuring "a voltage across an electrical connection of the … transmitter to the two-wire process control loop."
• A microprocessor performs loop diagnostics based upon the measured loop current and terminal voltage, and determines the resistance of the loop and the voltage of the power supply.
• Explicitly motivated by "high leakage or shunt current such as when moisture or some other electrical conductor contacts the electrical supply rail" — i.e., the identical failure mode ('642: humidity/salt corrosion raising transition resistance) the '642 patent recites.
• Uses an "on-demand loop characterization function," and in one embodiment acts "in response to receipt of a diagnostic command" (HART).

4.3 Secondary reference B — US 10,367,612 B2 (McCoy & Lauzon; Rosemount Inc.) = US 2017/0093533 A1 = WO 2017/058 527 A1, "Process variable transmitter with self-learning loop diagnostics" — cited in the German search report and in the "Family Cites Families" list

Verified from freepatentsonline.com/y2017/0093533.html, patents.justia.com/patent/10320535, and WO2017058527A1:

• Terminal voltage measurement circuitry measures a voltage at the transmitter terminals; a microprocessor performs loop diagnostics based on loop current and measured terminal voltage.
• The microprocessor "determines coefficients of a polynomial equation which relates loop current and terminal voltage during normal operation of the two-wire process variable transmitter and performs subsequent diagnostics based upon the coefficients of the polynomial."
• The loop model is expressly V_terminal voltage = V_power supply − I_loop current × R_loop.
• FIGS. 4A–4C show terminal voltage vs. loop current, upper and lower limits about the determined polynomial, and comparison of a subsequent polynomial with a baseline polynomial.
• "An automatic/self-learning loop characterization function … configured to generate and store baseline information related to power supply and loop resistance"; coefficients "generated at startup"; diagnostics include determining loop resistance and power supply voltage; detects high leakage/shunt current from moisture/contaminants in the terminal block.
• Diagnostics "based upon the coefficients" and "detecting variations in the process control loop based upon the coefficients."

This reference maps almost one-to-one onto L4, L5, L6, and onto dependent claims 4 and 6. Its disclosure is broader than US 9,182,256 B2 because it teaches the baseline-then-compare loop, not merely an on-demand measurement.

Timing note (flagged, not corrected): WO 2017/058 527 A1 published 2017-04-06 and US 2017/0093533 A1 published 2017-03-30 — both after the '642 2016-09-01 priority date. Their effective filing date is 2015-09-30 (US 14/871,850), which precedes 2016-09-01. They therefore qualify as prior art only under the § 102(a)(2)/§ 102(d) "effectively filed" pathway (a US patent-application publication and, if it designates the US and is published in English, a WIPO publication of an international application deemed published under § 122(b)) — not as § 102(a)(1) art. Any § 103 combination resting solely on this reference must be predicated on that effective date. US 9,182,256 B2 (granted 2015-11-10; earliest priority 2009-07-09) has no such timing issue and is a clean § 102(a)(1)/§ 103 reference.

4.4 Secondary reference C — DE 10 2007 062 919 A1 (Endress + Hauser GmbH + Co. KG)

Verified from the reference's own text:

• A voltage-measuring unit determines the actual loop current I_S via the voltage drop across an internal measuring resistor 7; a second voltage-measuring unit determines the load voltage (Bürdenspannung).
• "Speichereinheit … in einem vorgegebenen Messzyklus als Historienwerte abspeichert" — stores the determined operating/environmental conditions as history values in a memory integrated in the field device in a predetermined measuring cycle, and displays them as a curve.
• Limit values (Grenzwerte) are pre-set for the determined operating conditions, and on under-/overshoot the field device outputs an error message on its I/O unit and/or communicates it over the two-wire line to a remote control station.

This supplies art for L4's storage-of-a-per-device-record and L6's limit-value-triggered reaction/messaging, and supports claims 5 (tabular/curve storage) and 3 (limits set relative to a measured baseline).

4.5 Secondary reference D — US 5,481,200 (Voegle et al.; Rosemount Inc.), "Field transmitter built-in test equipment"

Grounded only indirectly, but reliably: the US 10,367,612 specification states verbatim that "Examples of such diagnostics and related aspects are shown and described in U.S. Pat. No. 5,481,200, issued Jan. 2, 1996 to Voegle et al." It is also the first entry in '642's own "Citations (9)" list. It is the generic teaching of built-in self-test in a field transmitter — i.e., moving operability checking into the device.

4.6 Secondary reference E — US 7,098,798 B2, "Process device with loop override"

Grounded on title/assignee (Rosemount) from the patent page's "Similar Documents" list only. As titled, it addresses overriding the loop current — the mechanism '642 uses for its "predefined reaction" (outputting a permitted loop current outside the measurement range). I flag that I did not retrieve its text and therefore do not rely on it as a primary teaching for L6.

4.7 References listed but not verified by me — treated as title-only

Because my tool-run terminated at its step limit, I did not retrieve substance for: DE 10 2006 030 774 A1 (Endress+Hauser Conducta, "Method for determining the load resistance for a transmitter"); EP 2 219 013 B1 (VEGA Grieshaber, "Energy production device for producing and simultaneously monitoring measured current"); DE 10 2011 082 018 A1 (Siemens); DE 29917651U1 (Siemens); US 2002/0145528 A1 (IFM Electronic); US 2008/0013226 A1 (Endress+Hauser Flowtec); US 2009/0110039 A1 (Kort); US 2009/0117873 A1 (Ferreira); US 2014/0363031 A1 (Siemens); US 8,598,865 B2; US 10,379,145 B2; EP 2 156 200 B1; RU 2 490 596 C1. I do not assign them disclosure content. Their titles alone, however, corroborate that (i) "determining the load resistance for a transmitter" and (ii) "simultaneously monitoring measured current while producing energy" were known aims in this exact field.

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5. Combination A (primary case) — '894 (Scholz) + US 9,182,256 (Rosemount) → claim 1 obvious

Why combine (motivation, articulated):

1. Same field of endeavor, same problem. Both are two-wire, loop-powered industrial transmitters; both address the identical physical failure: inadequate / creeping terminal voltage at high loop current caused by loop resistance and resistance at terminals (moisture, corrosion, contaminated terminal blocks). US 9,182,256 says so in terms ("moisture or some other conductive contact … at the supply rail," junction-box leakage).
2. '894 itself supplies the motivation by identifying its own deficiency. The '642 specification concedes that '894 "has the disadvantage of the need to periodically pass through the entire current range … independently of the measured values" and that this "requires synchronization between maintenance work and process control," concluding "Monitoring during normal operation is desirable." Where the primary reference itself flags the burden of periodic full-range sweeps, the motivation to adopt a continuous/normal-operation characterization from the art is legally adequate under KSR.
3. The secondary reference solves exactly that deficiency. US 9,182,256 measures the same two quantities (I, U_E) continuously/on-demand while the transmitter is running, without forcing the process loop through a test sweep and without passivating the host. Adding it to '894 merely substitutes a continuous characterization for a periodic one — a change in when the same measurement is made.
4. Reasonable expectation of success / predictability. Both references operate on the same observable quantities with the same physics (U_E = U_B − I_S·R_loop) and require no new hardware beyond what a two-wire transmitter already has (loop-current sense + terminal-voltage ADC). The only added step — retaining the baseline (I, U) data for later comparison rather than comparing to a fixed U_ES — is data storage and comparison, which is the routine work of a microprocessor.
5. Finite, predictable solutions. KSR: detecting a change in a known linear relationship by (a) re-measuring it and (b) comparing to a stored baseline is a predictable, indeed the obvious, engineering choice.

Net: claim 1 would have been obvious over '894 in view of US 9,182,256, and a fortiori over '894 + US 9,182,256 + DE 10 200 7 062 919 A1.

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6. Combination B (stronger, and closer to verbatim identity) — '894 + WO 2017/058 527 A1 / US 10,367,612 B2 → claims 1 and 6 obvious

This combination is close enough to warrant flagging as a § 102 risk as well as a § 103 risk, subject to the § 102(a)(2) timing pathway noted at § 4.3.

• L4 — '612: the microprocessor "generate[s] and store[s] baseline information related to power supply and loop resistance"; "determines coefficients of a polynomial equation which relates loop current and terminal voltage during normal operation"; coefficients are "generated at startup." Stored, device-specific (self-learned) parameters ⇒ an "individual signature."
• L5 — '612: "performs subsequent diagnostics based upon the coefficients of the polynomial"; FIG. 4C is expressly "comparison of a subsequent polynomial with a baseline polynomial"; diagnostics "detecting variations in the process control loop based upon the coefficients." That is a recursive (repeated) comparison against the stored baseline at the same loop current. "During normal operation" satisfies "during ongoing operation."
• L6 — '612: the baseline is used "to determine if the power supply, associated loop wiring, load resistance and electrical connections are all functioning properly such that the transmitter can output a correct current value," i.e., an alarm/diagnostic reaction on departing from the baseline. '894 supplies the concrete reaction (reduce I_S, signal an error/fault current).
• Claim 6 (coefficients of an equation system) — '612 teaches this literally: "determines coefficients of a polynomial equation … and performs subsequent diagnostics based upon the coefficients." Combined with '894's sweep-and-measure step, claim 6 reads on the combination.
• Claim 4 (two extreme loop currents + interpolation) — '612 derives a polynomial from measured (I, U) samples (a curve fit over the swept range ⇒ interpolation between measured points), and FIG. 4A is literally "terminal voltage versus loop current." '894 supplies the end-point sweep (min → I_SM).
• Claim 5 (table) — the specification itself presents "table" and "coefficients of an equation system" as interchangeable alternative embodiments of the same storage step, which is strong evidence that the table form is an obvious equivalent data-structure choice (and DE 10 2007 062 919 stores/plots the record as a curve in memory).

Motivation: identical — both references are two-wire industrial transmitters characterizing the same (loop current, terminal voltage) relationship to diagnose the same power/loop-wiring condition; '612's express attribute "self-learning" supplies precisely the per-device "individual signature" concept '894 lacks, and '612 is expressly aimed at eliminating the need for disturbance of normal operation.

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7. The predefined reaction (L6) and the "fault current" embodiment

The '642 specification's preferred reaction — output a permitted loop current outside the 4–20 mA range as a fast fault signal — is conventional and is corroborated by art in the same family of documents:

• '894 already signals the error (and reduces I_S).
• US 2014/0362487 A1 (Fetz et al.; Endress + Hauser Conducta; family of DE 10 2013 105 994 A1) discloses, for a two-conductor 4–20 mA field device, "the service program is embodied, in the case of a detected voltage reduction, to output an error signal, especially an error current, on the signal output," so "at a site remote from the field device, the error can be recognized." Verified text.
• US 7,098,798 B2 ("Process device with loop override") is titled to the same function (title-only grounding).

Because dependent claim 3 and the fault-current embodiment are not themselves claimed as independent subject matter beyond claim 1, this art is chiefly useful to show that the "predefined reaction" limitation is a finite design choice, not a point of novelty.

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8. Dependent claims 2–7 — element-by-element

Conclusion on dependents: claims 2–7 are each, at most, routine refinements or mere alternative data representations of the claim‑1 combination, and claim 6 in particular is squarely met by US 10,367,612/WO 2017/058 527 A1. None recites a structural or functional element absent from the combination.

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9. The claim-construction wrinkle that helps the obviousness case

The previously generated summary flagged that claim 1 stores the signature "as an individual signature of the two-wire measuring transducer," whereas the specification says "an individual signature of the current loop with the measuring transducer." For § 103:

• Under the broadest reasonable interpretation, "signature of the transducer" reads on any stored baseline that characterizes the transmitter's own terminal-voltage-vs-loop-current behaviour — which is exactly what US 10,367,612's "self-learning" per-device polynomial coefficients are (they are learned by the transmitter, stored in the transmitter, and describe that transmitter + its loop).
• If instead the "loop with the transducer" reading is adopted (narrower, per the specification and the German text: "individuelle Signatur des Messumformers (100)" / "of the current loop with the measuring transducer"), it is likewise met — '612's baseline characterizes "power supply and loop resistance," i.e., the loop-plus-device system.
• Either construction lands on the same prior art. This is not a case where claim construction rescues the claim.
• Separately, the grammatically truncated final clause of claim 1 ("leaves a predefined tolerance via the internal resistance…") is reproduced literally in the granted text and in US 2019/0195667 A1. For § 103 I read it in light of the specification's "leaves a predefined tolerance" (i.e., the measured input voltage deviates from the signature beyond the tolerance). Under that reading, '612's "upper and lower limits with respect to a determined polynomial" (FIG. 4B) is a straightforward anticipation of the tolerance band.

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10. Anticipated counterarguments and why they likely fail

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11. Secondary considerations

On the record available to me, there is no evidence of nexus-bearing secondary considerations:

• No unexpected-results evidence appears in the specification beyond the asserted (and expected) benefit of not passivating the host — which is exactly what US 10,367,612 already achieves.
• No licensing, industry-praise, or copying evidence is on the patent page.
• No commercial-success evidence tied to the claimed method is in the record; and in any event the assignee (ABB) is a large incumbent, so commercial-success nexus would require a showing that loop-diagnostics sales were attributable to the claimed method.
• No long-felt-but-unresolved need is shown: the DE 10 2005 047 894 family, US 9,182,256, US 10,367,612, and DE 10 200 7 062 919 all show the industry was already addressing terminal-voltage/loop-resistance diagnostics continuously through 2005–2015.
• The litigation posture is neutral (per the earlier "Litigation summary," no proceedings located), so there is no adjudicated validity record to weigh.

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12. Overall conclusion

Claim 1 is, in my assessment, invalid as obvious under 35 U.S.C. § 103. The strongest articulation:

Primary: DE 10 2005 047 894 A1 / US 7,358,744 B2 (Scholz). Discloses L1, L2, L3 and the reaction aspect of L6 (sweep loop current measured-value-independently from min to max while measuring input voltage across the internal resistance; compare to a threshold above U_EM; signal an error).
Secondary: US 9,182,256 B2 (Rosemount). Discloses measuring loop current and terminal voltage during transmitter operation, and determining loop resistance and supply voltage — supplying L4's device/loop-specific characterization and the repeated comparison of L5.
Further: WO 2017/058 527 A1 / US 10,367,612 B2 (Rosemount), as § 102(a)(2) art effective 2015‑09‑30: discloses storing a self-learning baseline ("coefficients of a polynomial equation" relating loop current to terminal voltage) obtained during normal operation, and subsequently comparing the re-derived polynomial against the baseline (FIG. 4C) to detect loop-resistance/supply changes — supplying L4, L5, L6 and dependent claims 4 and 6 essentially directly.
Optionally: DE 10 200 7 062 919 A1 (Endress+Hauser) for per-device history-value storage in field-device memory and limit-value-triggered error messaging (L4, L6, claim 5).
Motivation: same field, same failure mode (moisture/corrosion-driven terminal resistance / creeping loop resistance), and the applicant's own specification's statement that "monitoring during normal operation is desirable" over the periodic-sweep drawback of '894. Predictable combination of known elements; reasonable expectation of success; finite set of solutions (KSR).

Dependent claims 2–7 are likewise obvious, each being arithmetic on already-measured data (2, 3), a routine equivalent representation of a known linear electrical relationship (4, 5, 6), or a known placement of test points outside the live measurement band (7). Claim 6 carries the additional risk of anticipation under the § 102(a)(2) pathway, given US 10,367,612's express "coefficients of a polynomial equation."

Confidence and limitations (stated explicitly):

• High confidence in the disclosure content of '894/US 7,358,744 and US 9,182,256, US 10,367,612/US 2017/0093533/WO 2017/058 527, and DE 10 200 7 062 919, all of which I retrieved and quoted.
• Low/undetermined on the content of the nine-plus listed references I did not retrieve (DE 10 2006 030 774 A1, EP 2 219 013 B1, US 8,598,865 B2, US 10,379,145 B2, DE 10 2011 082 018 A1, US 7,098,798 B2, US 5,481,200, etc.). Additional § 103 combinations almost certainly exist among them — particularly around DE 10 2006 030 774 A1 ("determining the load resistance for a transmitter") and EP 2 219 013 B1 (simultaneous energy production and current monitoring) — but I will not assert content I did not verify.
• Statutory-date caveat (material): the WO 2017/058 527 A1 / US 2017/0093533 A1 branch of the analysis depends entirely on the § 102(a)(2)/§ 102(d) "effectively filed" doctrine and the reference designating the US and being published in English. That must be confirmed against US 14/871,850's priority chain before being relied on. Combination A does not depend on it.
• I performed a web-indexed analysis, not a litigation-grade prior-art search, and I did not consult the parties' file histories, any IPR petition, or the German/EP examination file beyond the search-report citation lists shown on the patent page. A definitive invalidity opinion would require claim-charting against the full texts of the un-retrieved references and confirmation of the effective-filing-date chain.