Phoenix Contact PSR Safety Relay Alternatives — the DAIDISIKE DA31

We already keep cross-reference notes for the Pilz PNOZ and the Allen-Bradley Guardmaster 440R, because those are the names customers most often arrive with when they want a force-guided safety relay sourced direct from the factory. Phoenix Contact's PSR line is the next one that keeps coming up — so here it is, built the same honest way: from Phoenix Contact's own public catalogue, not from anyone's manual or marketing, and with the places it doesn't fit called out rather than buried.

One framing point before the detail. “Replacing a safety relay” is not a part-number lookup. A safety relay is defined by five things: the safety level it can reach (PL / SIL and category), the input pattern it accepts (single/dual channel, E-stop vs. light-curtain vs. gate), the output contacts it offers (how many NO safety contacts, plus signalling), whether it does EDM and how it resets, and its width on the rail. Match those five and the swap is sound. Miss one — especially the input pattern or the EDM loop — and the relay will look fine on the bench and fail the function test. Everything below is about getting those five right against the PSR families.

What is the DAIDISIKE alternative to the PSR-MC?

The DA31 matches the 22.5 mm PSR-MC34-3NO-1DO family on safety level, input pattern, contact count and width; the one thing to align is the signalling output type. Phoenix Contact's PSR-MC is the 12 mm and 22.5 mm modular coupling-relay range. The workhorse 22.5 mm parts — for example PSR-MC34-3NO-1DO-24DC-SC (2700540) and the screw/spring variants PSR-MC34-3NO-1DO-24DC-SP (2700548), PSR-MC40-3NO-1DO-24DC-SP (2700570) and PSR-MC50-3NO-1DO-24DC-SP (2700564) — provide 3 NO safety contacts plus one digital signalling output, are force-guided, and reach PL e / SIL 3 on dual-channel E-stop or safety-gate inputs. There are 2 NO variants too (e.g. PSR-MC30-2NO-1DO-24DC-SP 2700499, PSR-MC70-2NO-1DO-24DC-SP 2702095) and a two-solid-state-output part (PSR-MC31-2SDO-1DO-24DC-SP 1015503).

The DAIDISIKE DA31 lands on the most common of these — the 3 NO PSR-MC34-class parts. It is a force-guided, 22.5 mm-wide, 24 V DC safety relay providing 3 NO safety contacts + 1 NC auxiliary, EDM, manual or automatic reset, dual-channel E-stop / safety-gate inputs, and a response time under 30 ms, rated to PL e / SIL 3 by force-guided construction. The functional fit is direct. The one detail to align is the auxiliary output: the PSR-MC34 carries a solid-state digital output (“1DO”) for signalling, while the DA31 gives you a hard NC contact. Both report status to your PLC; they wire differently. Tell us how the PSR-MC's DO is used and we confirm the DA31's NC mirrors it correctly — or flag it if your logic specifically needs a solid-state output.

Can a 22.5 mm DA31 replace a PSR-SCP relay?

For the safety-evaluation role, yes — same width, same PL e / SIL 3, same force-guided construction. The watch-out is whether the PSR-SCP was evaluating or only multiplying contacts. The PSR-SCP range is Phoenix Contact's 22.5 mm safety coupling / expansion relay line. Variants in service include the PSR-SCP ESP4 (2981020), PSR-SCP ESA4 (2963750), PSR-SCP ESAM4 (2981114) and PSR-SCP MXF2 (2903254), alongside the SPP build PSR-SPP ESP4 (2981017). They are force-guided and rated to the same PL e / SIL 3 ceiling as the DA31, on the familiar dual-channel E-stop and safety-gate input pattern.

Where a PSR-SCP is acting as the standalone safety evaluator — reading the E-stop or gate, doing the dual-channel and cross-fault logic, driving the machine's contactors through monitored outputs — the DA31 is a clean functional replacement: 22.5 mm, 3 NO + 1 NC, EDM, PL e / SIL 3. Where a PSR-SCP is instead a pure coupling / expansion module — multiplying the contacts of an upstream evaluation relay, not deciding anything itself — a single DA31 is not the like-for-like; there you keep an evaluator and add a contact-expansion stage. The part number tells us which case you have. This is the single most common mistake on a PSR-SCP swap, so we always ask before quoting.

The obsolete-part hook: what replaced 2981114 and 2981127?

Several older 22.5 mm PSR-SCP parts have been discontinued and steered toward the PSRmini line; the DA31 lets you stay force-guided at PL e / SIL 3 without the migration. If you are holding an obsolete 2981114 (PSR-SCP ESAM4) or 2981127, Phoenix Contact's own catalogue path points toward the newer PSRmini family — a coupling relay such as 2700524 is the suggested successor direction. That is a valid route if you want to stay inside the Phoenix Contact ecosystem and adopt the 6 mm push-in format. But it is a migration: different footprint, different terminal scheme, often a BOM and panel re-layout.

The DAIDISIKE DA31 is the alternative for buyers who would rather not migrate. It keeps the 22.5 mm footprint the obsolete PSR-SCP occupied, keeps the force-guided construction and the PL e / SIL 3 ceiling, and covers the same E-stop / guard-monitoring duty with 3 NO + 1 NC and EDM. The honest condition, again, is the evaluate-vs-multiply question above: confirm the obsolete unit was the evaluator before you treat one DA31 as its one-for-one replacement.

How does the DA31 cross-reference to each PSR family?

DA31 maps to the 22.5 mm PSR-MC34 and PSR-SCP (force-guided, PL e / SIL 3); it is not a width match for the 6 mm PSRmini, and there is no equivalent to the configurable PSR-TRISAFE. This table is a starting map from public catalogue data, not a drop-in part number. Confirm against your installed unit's data.

The pattern across the PSR families is the same one we see on every force-guided safety relay: the safety function — dual-channel input, monitored reset, force-guided NO outputs, EDM contactor feedback — is portable, and the divergence is at the edges. Phoenix Contact's edge is breadth: a 6 mm PSRmini for panel density and a PSR-TRISAFE for configurable logic, two ends the DA31 deliberately does not chase. In the broad middle — the 22.5 mm force-guided E-stop / gate relay — the DAIDISIKE DA31 is the like-for-like, and we ran the same exercise against the Allen-Bradley Guardmaster 440R range with the method unchanged.

PSR-TRISAFE vs. a normal force-guided relay

The PSR-TRISAFE is a programmable safety controller; the DA31 (like the PSR-MC) is a fixed-function relay. They solve different problems, so there is no DA31 equivalent to the TRISAFE — by design. The PSR-TRISAFE-S (2986229) is configured in software, evaluates many inputs, and can drive multiple safe outputs with programmable logic — it is a small safety PLC. A force-guided relay like the PSR-MC, PSR-SCP or the DAIDISIKE DA31 does one wired safety function with no programming. If a machine genuinely needs configurable logic across several zones, a relay — ours or Phoenix Contact's — is the wrong tool and a configurable controller is correct. But a great many machines need exactly one reliable E-stop or one guard-door channel, and for those a programmable controller is cost and complexity you don't need; the DA31 is the honest, cheaper fit. We will tell you plainly which side of that line your application sits on.

Pilz PNOZ vs PSR vs DA31 — where the DA31 sits

Pilz PNOZ, Phoenix Contact PSR and the DAIDISIKE DA31 are all force-guided safety relays reaching PL e / SIL 3; the DA31's position is factory-direct sourcing of the standard duty. Buyers comparing a Pilz PNOZ against a Phoenix Contact PSR are usually weighing brand, contact configuration and price for the same job: a monitored E-stop or gate. The DA31 enters that comparison on the procurement axis. As the Foshan factory that builds it, DAIDISIKE sells the DA31 direct — MOQ one set, typical 3–15 day lead time, CE self-declaration with IEC 61508 / ISO 13849-1 PL e / SIL 3 force-guided construction. That is the lever for teams facing long PSR or PNOZ lead times, obsolete part numbers, or a BOM that needs to come down without dropping a safety level. It is not a claim of feature parity with every PSR or PNOZ variant — it is a like-for-like on the common 22.5 mm force-guided relay, sourced direct.

Is naming Phoenix Contact legal, and how do you keep this honest?

Naming a competitor's product to describe a compatible alternative is nominative reference and is legitimate; the comparison stays honest by using only Phoenix Contact's published catalogue data. We reference Phoenix Contact and the PSR-MC, PSRmini, PSR-SCP and PSR-TRISAFE names to tell you what the DAIDISIKE equivalent is — normal, lawful comparison, no implied partnership or endorsement. What we deliberately do not do: we don't reproduce Phoenix Contact's manuals, we don't use their trademarks or logos as our own, and we don't quote a price or a parameter we can't confirm from their public catalogue. Every PSR part number above is a real Phoenix Contact catalogue number; the DA31 figures are DAIDISIKE's own. Where we are unsure which role your specific PSR-SCP plays, the page says “send the part number” rather than pretending to a precision we don't have for your build.

Send us the safety function (E-stop, gate, light curtain), the input channels, the contact count you need, your EDM/reset scheme and the PSR part number you are replacing, and we will confirm the DA31 fit — or tell you plainly when PSRmini width or PSR-TRISAFE logic is the better tool. Our wider sourcing and OEM detail lives on the safety relay manufacturer page.