What a Written Cross-Reference Report Actually Contains — and What It Cannot Certify for You
What a Written Cross-Reference Report Actually Contains — and What It Cannot Certify for You
A maintenance engineer at a bottling line in Sverdlovsk sends us an inquiry: their MELSEC iQ-R analog input module is failing, the line is down, and they want a written cross-reference report that names a candidate they can buy instead. The report that comes back walks twelve axes, marks each axis with one of three verdicts, and stays deliberately silent about six things it does not certify on the buyer's behalf. This article is a guided tour of what that report contains — anchored to a Mitsubishi MELSEC iQ-R and FX5 cross-reference example — and how to read it when it lands in your inbox.
The report is a methodology, not a verdict
A written cross-reference report is not a one-line recommendation. It is a structured walk through twelve axes that decide whether two industrial automation modules are interchangeable — form, fit, electrical, function, firmware, protocol, and so on. Each axis carries one of three verdicts: matched, differs, or unknown. The unknown verdict is the one most engineers skip past, and it is the one that matters most. A cross-reference report that fills in every axis as matched is not telling you the truth; it is telling you the author skipped the verification step on the axes where the manufacturer does not publish enough data to score.
For the MELSEC iQ-R series, the kind of cross-reference request we receive most often involves the analog I/O family. A buyer may have an R60AD8-G (eight-channel voltage/current analog input) installed and need to know whether the channel-isolated R60ADI8-H can replace it without re-wiring the field terminals. The report walks the twelve axes for that pair, and the verdict on any axis where the manufacturer does not publish the same parameter set as for the original ends up as unknown. The unknown verdict is not a confession of failure; it is the honest answer when the datasheets do not align.
The twelve axes the report walks through
The substitution framework used on this site has twelve axes. They are listed here in the order a report walks through them, with the Mitsubishi-specific question each axis answers.
Form, fit, outline, and mounting asks whether the two modules share the same physical envelope, the same DIN-rail or panel-mount interface, and the same module width in the rack. For Mitsubishi iQ-R, both the R60AD8-G and R60ADI8-H are single-slot modules that mount on the same base unit, so this axis is matched on the visible outline. The same is true if you compare an FX5-20PG-P (pulse-train positioning module for the FX5 rack) with its FX5-20PG-D differential-output sibling — same form factor, same slot count. The axis turns to differs when a buyer tries to swap an iQ-R module for an FX5 expansion block, because the rack architecture itself differs and no axis below this point matters.
Dimensions asks whether the depth, weight, terminal cover swing radius, and panel cutout (where applicable) match. For DIN-rail-mounted modules the depth question reduces to terminal-block swing clearance, which is matched across the iQ-R analog family. For panel-mount HMI panels this is the axis that often differs between an FX5-compatible panel and an iQ-R-compatible panel, because the cutout and bezel are family-specific.
Terminal and interface assignment is the axis where most cross-reference failures show up. It asks whether the terminal numbering, the supply-rail terminal position (L+ and M on a 24 VDC module), the I/O channel-to-terminal mapping, and any front connectors or bus connectors match. The iQ-R analog family uses the same one-piece terminal block across the R60AD8-G, R60DAV8, R60DAI8, R60RD8-G, and R60AD8-G, but the channel-to-terminal mapping on the analog input module differs from the analog output module — they share the form factor but not the terminal assignments. A cross-reference report that says "terminal layout matches" without flagging which terminals carry what signal is misleading.
Electrical parameters asks whether supply voltage range, per-channel current, total module current, output voltage rating, surge and short-circuit protection, and module power dissipation match or exceed the original. The R60AD8-G runs on 24 VDC, draws roughly 200 mA, and supports ±10 V, 0 to 10 V, 0 to 5 V, 1 to 5 V, 4 to 20 mA, and 0 to 20 mA input ranges. If a candidate replacement accepts only voltage inputs and not current, the report marks this axis as differs — even if everything else matches — because the channel cannot be wired to a 4 to 20 mA transmitter without an external resistor.
Function and I/O specification is the axis that decides whether the new module does the same job as the old one. Channel count, signal type (digital, analog, RTD, thermocouple, high-speed counter, PTO), resolution, accuracy, isolation (channel-to-channel or group), diagnostic coverage, and any module-specific features (high-speed counting, pulse-train output, PID loops) are all scored here. For the FX5-4LC temperature-input module, this axis is the one where a buyer moving from an FX3U-4LC will see a differs verdict on the supported thermocouple types and the cold-junction compensation behavior. For the LJ71GF11-T2-CM CC-Link IE Field head module, the function axis covers the station count, the cyclic transmission size, and the transient transmission support — all of which differ between CC-Link IE Field and CC-Link IE Field Basic.
Firmware version asks whether the two modules are compatible with the same CPU firmware and engineering software. The iQ-R CPU firmware version determines which analog module revisions will work in a given slot. The FX5U-32MT/DS engineering environment (GX Works3) treats the FX5-20PG-P and FX5-20PG-D differently — they share the project library header but require a different positioning block to be instantiated. A cross-reference report that does not flag the firmware-version axis is leaving the question of "will the existing program load" unanswered.
Communication protocol is the axis that decides whether the module talks to the rest of the network the same way. For iQ-R modules attached to a CC-Link IE Field network, this axis covers the station type, the profile, and the link-scan behavior. For an FX5 module on a CC-Link IE Field Basic network, the protocol is the lightweight variant — a cross-reference report between an iQ-R-class CC-Link IE device and an FX5-class CC-Link IE Field Basic device will mark this axis as differs, even if both are "CC-Link IE" in casual conversation.
Mechanical parameters are usually folded into form/fit but are listed separately for vibration and shock tolerance, fastener torque on terminal screws, and connector insertion force. For most iQ-R and FX5 modules these match within the family.
Environmental class and ingress/temperature asks whether the ambient temperature range, humidity tolerance, and IP rating match. Indoor cabinet modules typically match; outdoor-mounted HMI panels and remote I/O blocks are where this axis differs.
Materials covers housing flammability rating, terminal plating, and any RoHS or REACH declarations. For most modern Mitsubishi modules this axis is matched; for older iQ-R modules manufactured before the RoHS revision, it is a differs verdict that the buyer needs to know about for EU-bound lines.
Certifications and lifecycle is the axis where the report gets honest about what the manufacturer no longer supports. A module that is in the "planned discontinuation" stage carries a lifecycle caveat that a new module does not. This is also where the report flags whether the candidate replacement has UL, CE, KC, or other regional certifications that the original carried.
The claim ladder, and why the report stays at level 2 or below
A written cross-reference report from this desk uses a five-level claim ladder. Level 0 is a manufacturer-documented level-0 verdict — a state the original manufacturer explicitly confirms in a cross-reference document or product change notice. Level 1 is visually similar outline. Level 2 is mounting and terminal interface matches on paper. Level 3 is functionally and electrically rated at or above the original. Level 4 is customer-qualified substitute — a state only the customer can reach after their own bench and program-migration testing.
For the MELSEC iQ-R analog input family, almost no replacement pair reaches level 0. The modules look alike, the terminals align, the I/O mapping is similar — but the firmware revision requirements, the channel-to-terminal assignment, and the supported signal types shift across revisions. A report that claims level 0 status for an R60AD8-G to R60ADI8-H swap is not telling you the truth. The honest verdict for that pair is level 2 with an explicit unknown on the firmware-version axis.
The report deliberately avoids a vocabulary of absolute interchangeability — phrases such as "absolute interchangeability," "one-to-one match," and the unqualified claim that one module "replaces" another without qualification. These phrases show up in informal channels and on third-party marketplaces; they do not show up in a written report that has been read by an engineer who has been bitten by one before. The report's job is to walk the buyer through what is and is not matched so they can decide whether to take the candidate to a bench test themselves. Verify against the original manufacturer datasheet and your own qualification process before commissioning any candidate from a cross-reference report.
The fail-safe case the report refuses to score
A written cross-reference report refuses to score the substitution question when the original module sits on a safety circuit. If the original MELSEC iQ-R analog input module is reading a safety-rated signal — a guard-door interlock, an emergency-stop loop, a two-hand control, a light-curtain output — the report returns a single-line refusal: do not substitute here, refer the question back to the customer's safety assessment against IEC 61508 and ISO 13849. The desk does not score axes where the safety case changes, does not write a verdict, and does not recommend a candidate. The safety function has to be re-qualified end to end by the customer's safety team with the original manufacturer's documentation, and any cross-reference between two safety-rated modules is the customer's process to run, not the supplier's. This is the one cross-reference request that the report does not attempt to answer, regardless of how straightforward the module pair looks on the outline.
What the report does not certify
A written cross-reference report does not certify six things, and a buyer who assumes it does will end up with a module on a shelf and a line that still does not run.
The report does not certify that the candidate module will run the existing program. Program portability depends on the CPU firmware, the engineering software version, the function blocks referenced, and the module-specific library calls. Two modules that look identical on paper can require different positioning blocks, different analog scaling routines, or different interrupt handlers in the program. The report cannot tell you whether your program will load — only the customer-qualified substitute process can.
The report does not certify any safety integrity level. If the original module sat on a safety circuit, the report refuses the substitution question outright. For non-safety modules, the report still does not certify a SIL/PL rating on the candidate — that rating is a property of the specific module and its manufacturer documentation, not a property of the cross-reference pair.
The report does not certify regional compliance. Whether a module carries EAC, TR CU, CE, UL, or any other regional marking is a property of the specific module and the specific revision, not a property of "the cross-reference pair." A buyer in Russia or the CIS who intends to clear customs with a module that has not been tested against the relevant Technical Regulation is the buyer who takes the regulatory risk, not the report writer. We do not issue EAC declarations, we do not refer buyers to a certification body, and we do not state that a module "complies" with any regulation. The importer's own compliance process owns that decision. We screen end users and end uses, classify before quoting, and decline transactions that cannot be screened.
The report does not certify lead time, price, or stock. Those three items move with the quotation that accompanies the report, and the quotation is conditional on the per-line conditions the buyer has agreed to. A report can list candidate modules that exist in the catalog, and it can say "this MPN is what we are pricing on this quotation," but it cannot say "this MPN is in stock and will arrive in three days." That kind of statement belongs on the quotation, not on the cross-reference report.
The report does not certify that the candidate module is free of counterfeit risk. Counterfeit screening is a separate process — pre-dispatch photos, label etching, firmware read-back, and where applicable a third-party lab report — that runs against the specific unit the buyer will receive. The cross-reference report points to the candidate module; it does not grade the unit you will be shipped.
The report does not certify that the substitution is the right commercial decision. Whether the buyer should buy a new-surplus candidate, a refurbished candidate, a used candidate, or wait for the manufacturer to re-stock the original is a question that depends on the buyer's downtime cost, their qualification budget, and their risk tolerance. The report walks the technical axes; the commercial decision is the buyer's.
Independent distributor boundary
This site operates as an independent China-based industrial automation distributor and sourcing desk. We are not an authorized distributor, franchised partner, or factory agent for Mitsubishi, Siemens, ABB, Schneider Electric, Omron, Panasonic, SICK, Festo, Delta, Phoenix Contact, or any other manufacturer represented in the catalog. Cross-reference reports are produced by our engineering team from publicly available manufacturer datasheets, from catalog records we hold, and from prior qualification work our customers have shared with us; they are not endorsed or reviewed by the original manufacturer. The verdict on every axis is ours, not the manufacturer's. Where the report and the manufacturer's own cross-reference documentation diverge, the manufacturer's documentation wins — and that is why we ask every buyer to verify against the original manufacturer datasheet and your own qualification process before commissioning.
When to ask for the report, and how to use it
Ask for a written cross-reference report when you have a specific module you need to replace, a clear set of constraints (slot width, I/O count, signal type, protocol, certification region), and a willingness to walk through the twelve axes before you commit to a substitution. Do not ask for one when the answer you want is "buy this and it will work." That answer does not exist in a written report — it exists, if anywhere, only after the customer has run a bench test against the candidate and confirmed the program migration.
When the report lands, read it in this order. First, look for the axes marked differs. Those are the ones that change the wiring, the program, or the cabinet layout. If any of them is on a safety circuit, stop and return the report for re-evaluation against your safety case. Second, look for the axes marked unknown. Those are the ones the manufacturer has not published enough about for the report to score. Decide whether your qualification process can cover them or whether they are deal-breakers. Third, look at the matched axes. Those are the easy wins. They do not justify a substitution by themselves, but they are the basis on which the rest of the decision rests.
A cross-reference report is a starting document, not a closing document. Its job is to put the buyer in front of the right questions and the right unknowns, so that the bench test, the program migration, and the cabinet re-work happen with eyes open. The line that comes back online fastest is the line where the engineer who reads the report treats every axis marked differs as a work item and every axis marked unknown as a question to bring to the original manufacturer or to the engineering team that owns the program.
The practical next step
If you have a Mitsubishi MELSEC iQ-R, FX5, or Q-series module that needs a written cross-reference report, send us your BOM or request a quote through the inquiry form with the original MPN, the application context (which line, which slot, what the module is wired to), and the constraints you cannot move on (signal type, channel count, protocol, regional marking) through the inquiry form. The desk will run the twelve axes against the candidate modules in the catalog and return the report with matched, differs, and unknown verdicts on each axis. The report does not replace your qualification; it sets it up so it can finish quickly. Reference the original MPN in the subject line so the report goes to the right engineer on our side. Cross-reference reports and per-line quotations are produced through the procurement workflow; the BOM intake form on the procurement page is the fastest way to attach an existing cross-reference request to a broader sourcing conversation. Verify against the original manufacturer datasheet and your own qualification process before commissioning any candidate from the report.
FAQ
What is a written cross-reference report for an industrial automation module?
A structured walk through twelve axes — form and fit, dimensions, terminal assignment, electrical parameters, function and I/O specification, firmware version, communication protocol, mechanical parameters, environmental class, materials, and certifications and lifecycle — for two modules identified by their manufacturer part number. Each axis carries one of three verdicts: matched, differs, or unknown. The report is a methodology document, not a one-line recommendation.
Does a cross-reference report certify that the candidate module is interchangeable without any engineering work?
No. A written cross-reference report from this desk deliberately avoids the vocabulary of absolute interchangeability — phrases that claim a candidate is wholly substitutable without question, a plug-compatible swap, or that one module replaces another without qualification. For MELSEC iQ-R and FX5 modules, almost no replacement pair reaches the level 0 manufacturer-documented verdict. The highest honest verdict for most pairs is level 2 mounting and terminal interface matches on paper, and only the customer's own qualification process can reach level 4 customer-qualified substitute.
What does the report not certify for the buyer?
Six things: program portability on the existing CPU, safety integrity level for safety circuits, regional compliance such as EAC TR CU CE UL, lead time and price for the candidate, counterfeit screening of the specific unit shipped, and the commercial decision between new-surplus refurbished used and waiting for the original. The report walks the technical axes; the rest belongs to the buyer's qualification, compliance, and procurement teams.
Why does the report include an unknown verdict on some axes?
Because the manufacturer does not always publish enough data to score an axis. The R60AD8-G and the R60ADI8-H, for example, share a form factor and a supply rail, but the manufacturer does not publish the same channel-to-terminal mapping table for both modules at the same revision. An honest report marks that axis as unknown rather than guessing. The unknown verdict tells the buyer which axes their qualification process must cover.
How is a written cross-reference report different from a third-party cross-reference table?
Third-party cross-reference tables typically list a single candidate module per line and claim compatibility. They rarely score the twelve axes, almost never mark an axis as unknown, and use the vocabulary of absolute interchangeability that this site's report deliberately avoids. A written cross-reference report is the document a buyer reads when they want to know why the candidate might or might not work, not the document a seller hands over to close a transaction.
When should a buyer ask for a written cross-reference report?
When the buyer has a specific MPN to replace, a clear set of constraints (slot width, I/O count, signal type, protocol, regional marking), and a willingness to read the twelve axes before committing. The report is not the right document for a buyer who wants a one-line answer; the report is the right document for a buyer who wants to walk the methodology so their bench test and program migration run with eyes open.
What is the deliverable after a buyer sends the inquiry?
The report itself, plus a quotation that lists the candidate module by MPN with the condition (new surplus, refurbished, or used) stated per line. The quotation carries the price, the MOQ, the lead time per order, and the screening statement that applies to every shipment leaving the desk. Cross-reference report and quotation are two different documents; the report walks the technical case, the quotation closes the commercial one.
Data Notes
Cross-reference methodology described in this article is based on the twelve-axis framework published on this site and on manufacturer datasheets available as of September 2026 for the MELSEC iQ-R and FX5 series. Module part numbers referenced (R60AD8-G, R60ADI8-H, R60DAV8, R60DAI8, R60RD8-G, FX5-20PG-P, FX5-20PG-D, FX5-4LC, FX5U-32MT/DS, LJ71GF11-T2-CM) are catalog entries on this site; per-line condition, price, and lead time are confirmed on the quotation. The axis framework is internal documentation last reviewed 2026-09-25. Last reviewed 2026-09-25. This article does not constitute a cross-reference verdict for any specific module pair; the verdict is produced only when a buyer submits the original MPN, the application context, and the constraints through the inquiry form.
About the author
By aoctrl sourcing desk — an independent China-based industrial automation distributor and sourcing desk, not an authorized distributor for any manufacturer represented on this site. Send cross-reference requests through the inquiry form with the original MPN in the subject line.