Pilz PNOZ Safety Relay Alternatives — DAIDISIKE DA31 Equivalents

We keep cross-reference notes for the brands customers most often arrive with — and in the safety-relay category that brand is PILZ. The word “PNOZ” turns up in inquiries the way “light curtain” does, because PILZ launched the first E-STOP safety relay (the PNOZ) in 1987 and the name stuck to the whole product class. So when an engineer asks for a “PNOZ alternative,” they may mean: I have a single-function safety relay, what do I buy instead. This page answers that, built the same way we build every cross-reference — from PILZ's own published specs and our own DA31 datasheet, never from a copied manual.

A PNOZ replacement is an engineering change, not a part-number lookup. Pilz order numbers remain Pilz identifiers; DA31 and the separate DA31-B customer-specification variant must not be conflated. Compare the complete safety function, input diagnostics, output load, reset and feedback, safety data and installation envelope. DA31 EDM and monitored-reset equivalence are not established by the currently cited specification.

What is a PNOZ, and what is the DAIDISIKE DA31?

A safety relay evaluates the inputs and fault conditions documented for its specific operating mode. Internal force-guided contacts support fault detection, while a supported external feedback circuit monitors separate switching devices. Neither two input channels nor force-guided construction alone establishes every cross-short, restart or external-device diagnostic needed for a machine-level PL claim.

PNOZ X contains classic relay variants, PNOZsigma contains compact fixed-function and specialized units, and PNOZmulti is configurable. Match the precise model to the required function. DA31 manufacturer data lists a dual-channel safety relay, three N.O. safety contacts plus one N.C. auxiliary signalling contact and release response below 30 ms. Supporting documents are required for the target safety function; DA31-B is a separate variant with its own specification.

Which PNOZ does what? A quick family map before you cross-reference

Match the PNOZ family to the function first; only then pick the DAIDISIKE part. The PNOZ catalogue is large because it spans single relays, timers, two-hand controllers and configurable controllers. Here is the honest map of the real families and a few anchor models, so you know whether a single DA31 is even the right shape of answer.

The family map defines which functions need investigation. A PNOZ s3, s4, X2.8P or X3 name does not by itself establish DA31 equivalence. A timer, two-hand unit, expansion module or configurable controller has additional behaviour that must be retained; a plain contact-count comparison cannot replace it.

DA31 vs PNOZ s4 vs PNOZ X2.8P — the side-by-side

Compare the exact models, including their actual dimensions. Pilz lists PNOZ s4 750104 and PNOZ X2.8P 777301 at 22.5 mm. DA31 is specified at 22.6 mm, so there is no claimed width saving here. The table is a requirements comparison; unknown DA31 diagnostics remain unresolved, not assumed equal.

Where the columns read “per PILZ datasheet,” that is deliberate — we will not put a number in a PILZ column unless it is published, and exact response-time and contact-rating figures vary by PNOZ variant. Pull them from your unit's label and confirm against PILZ's own datasheet. The DA31 column is from DAIDISIKE's published spec.

What is the equivalent of a PNOZ X3, and what about PNOZ s3?

PNOZ X3 and X3P require their complete order numbers and circuits. Their three safety N.O. contacts and auxiliary signalling contact can be compared with DA31, but supply variants, reset and feedback must be checked separately. A matching contact arrangement does not establish input diagnostics or monitored-restart equivalence; DA31 is a 24 V DC candidate, not a universal AC/DC replacement.

The PNOZ s3 750103 is 17.5 mm wide, with two N.O. safety contacts and one semiconductor signalling output. Compare all used circuits against DA31, including status output polarity and load. DA31 requires a 22.6 mm installation envelope; an extra safety contact is not proof that its reset or feedback behaviour matches. Ask for current quotes after the engineering comparison is complete.

What to match before you swap any PNOZ for a DA31

Six requirement groups start the assessment; collect the installed unit's full manual and schematic. This is the same discipline we apply to every brand cross-reference.

• Safety function — identify the selected documented E-STOP, gate or OSSD input mode. These alternatives do not imply that one DA31 can combine three independent safety functions.
• Input channels — single-channel, or the architecture and fault diagnostics required by the assessed function. Two channels alone do not establish the required PL/SIL.
• Output contacts & rating — how many NO enabling contacts and any NC signalling contact, plus switching current. DA31 = 3NO+1NC.
• EDM / reset — is external device monitoring used, and is reset automatic or monitored-manual?
• PL / SIL target — from your risk assessment (DA31 is PL e / SIL 3).
• DIN width & supply — panel space (DA31 is 22.6 mm) and 24 V DC supply.

Send those six off your installed safety relay for a documentation-led DA31 assessment; unresolved requirements may mean it does not fit — for instance, if you actually need a controller, a two-hand module, or a higher switching current than a single DA31 provides. The wider method and the other brand cross-references (such as our Allen-Bradley Guardmaster alternatives) live in the brand replacement & compatibility guide.

Is naming PILZ and PNOZ legal, and how do you keep this honest?

Pilz and PNOZ names identify the comparison targets; no affiliation or endorsement is implied. This is a documentation-based sourcing checklist, not a legal opinion or compatibility declaration. Use Pilz primary sources for the exact order number, and separate DAIDISIKE documentation for DA31. Do not transfer competitor part numbers, certificate identifiers or circuit functions to the proposed replacement.