The DA31 series safety relay by DAIDISIKE is a compact, reliable device for industrial safety, monitoring emergency stops, safety light curtain OSSD signals, safety door interlocks and two-hand controls. Used in industries like CNC, robotics, and hydraulics, it is rated to EN ISO 13849-1 Cat. 4 / PL e and IEC 61508 SIL 3 per the manufacturer's specification. Its ultra-slim 22.6 mm housing, dual-channel PNP/NPN input and separate transistor status output help streamline installation and reduce wiring complexity.
12A (distributed across all safety output contacts)
Contact Resistance
<100 mΩ
Minimum Load
10mA / 5V
Contact Material
AgSnO2 + 0.2 µm Au
External Output Fuse
5A gL/gG
Release Response Time
<30ms (from input to output)
Electrical Life
80,000 operations
End-of-line Detection Resistance (safety edge / safety mat inputs)
1 kΩ – 10 kΩ
Rated Impulse Withstand Voltage
2.5 kV
Pollution Degree
2
Safety Level
EN ISO 13849-1 Category 4 / PL e; IEC 61508 SIL 3 (manufacturer specification)
Operating Temperature
-25°C to +85°C
Storage Temperature
-40°C to +105°C
Operating Humidity
35% – 85% RH (no icing or condensation)
Installation Method
Standard 35 mm DIN rail / spring clip
Dimensions
112mm × 99.5mm × 22.6mm
Weight
172 g
Protection Grade
Housing IP30, terminals IP20 — install inside an IP54 cabinet or enclosure
Housing Material
Flame-retardant PA66
Certification
Contact factory for certification documents
Technical Parameters of DA31 Series Safety Relay
The technical parameters of the DA31 series focus on safety performance and electrical characteristics. The power supply is 24V DC, with a tolerance range of +10% to -20%, and power consumption of 2.9W. The input stage is a dual-channel safety input that accepts either PNP or NPN signal sources, with four DIP-switch selectable input modes (emergency stop, safety light curtain OSSD, safety door interlock, two-hand control). The output provides 3 forcibly guided normally open safety contacts (13/14, 23/24, 33/34) and 1 normally closed auxiliary contact (41/42), rated AC-1 6A/250VAC with a maximum total current of 12A, plus a separate transistor signalling output below 500mA at 24V DC. The response time is less than 30ms, ensuring quick release. The operating temperature range is -25°C to +85°C and storage is rated -40°C to +105°C. The module is rated to EN ISO 13849-1 Cat.4/PLe and IEC 61508 SIL 3 according to the manufacturer's specification. The housing is flame-retardant PA66 with IP30 protection (IP20 at the terminals), so the module is designed to be mounted inside an IP54 cabinet or enclosure on a standard 35 mm DIN rail. Certification documents are not stated in the current factory documentation — please contact us for these.
Working Principle of DA31 Series Safety Relay
The core working principle of the DA31 series safety relay is based on a dual-channel safety input architecture: two independent input channels are monitored, so the safety function does not depend on a single channel. When the connected safety device is actuated, the module drops out and the forcibly guided contacts open to remove power from the hazardous machine function.
The specific workflow is as follows:
Input Detection: The dual-channel safety input receives signals from the connected safety device — an emergency stop button, a safety light curtain's OSSD outputs, a safety door interlock switch or a two-hand control station. Both PNP (sourcing) and NPN (sinking) signal sources are accepted.
Mode Selection: A DIP switch selects which of the four input classes the module supervises (emergency stop, light curtain OSSD, door interlock, two-hand control), so one part number covers all four applications.
Output Control: Once the input is valid, the three normally open safety contacts close to supply power to actuators such as motor contactors. The release response time is <30ms, ensuring quick disconnection in emergency situations. A separate transistor signalling output (<500 mA / 24 V DC) reports status to the PLC.
Fault Handling: The module uses forcibly guided (positively driven) contacts, mechanically linking the normally open and normally closed contacts so they can never be closed at the same time. A welded safety contact is therefore revealed by the auxiliary contact instead of failing silently.
Application Extension: In safety light curtain applications, when an intrusion is detected by the light curtain, the input is interrupted, and the relay output stops machine operation. The same module also covers emergency-stop, safety door interlock and two-hand control circuits.
Note: the DA31 carries a reset selector — the factory wiring diagram shows the SRC/SR terminals configured either for manual reset or, when linked, for automatic reset. External device monitoring (EDM) feedback loops and cross-fault detection are not stated in the current factory documentation for the DA31. Please contact us for the manual if your safety circuit requires these functions.
Frequently Asked Questions
What is the difference between a safety relay and a safety PLC?
A safety relay like the DA31 is a hardwired, fixed-function device that monitors emergency stops, safety light curtains or door switches through dual-channel redundant inputs and cuts output in under 30 ms. A safety PLC is programmable and scales to many zones and complex logic. For a single machine or a few safety functions, the DA31 is faster to wire and lower cost.
What safety standards and performance level does the DA31 meet?
According to the manufacturer's specification the DA31 is rated Category 4 / Performance Level e per EN ISO 13849-1 and SIL 3 per IEC 61508. It uses dual-channel safety inputs and forcibly guided (positively driven) contacts, so the normally open and normally closed contacts can never be closed at the same time and a welded contact becomes detectable rather than failing silently. Certification documents should be requested from the factory.
What input modes and signal types does the DA31 accept?
The DA31 has a dual-channel safety input that accepts both PNP (sourcing) and NPN (sinking) signal sources, so one part number works with European-style and Japanese-style sensors alike. A DIP switch selects one of four input modes: emergency stop, safety light curtain OSSD, safety door interlock, or two-hand control.
How is the DA31 wired and mounted?
The DA31 is a DIN-rail module measuring 112 × 99.5 × 22.6 mm — a 22.6 mm width that lets more safety circuits share the same rail length in a tight cabinet. Safety contacts use IEC-standard terminal designations (13/14, 23/24, 33/34 for the safety N.O. contacts and 41/42 for the auxiliary N.C. contact), so wiring drawings and inspection are unambiguous.
What outputs and contact ratings does the DA31 provide?
The DA31 provides 3 forcibly guided normally open safety contacts plus 1 normally closed auxiliary contact for status signalling. Safety contacts are rated AC-1 6 A / 250 VAC with a maximum total current of 12 A across the module. A separate transistor signalling output (<500 mA, 24 V DC) reports run/stop status to a PLC without using up a safety contact. The DC contact rating appears with two different values in the factory source documents (DC-13 4 A/24 VDC and DC-1 6 A/24 VDC) — contact us to confirm the applicable value for your load type.
