SICK RLY3-EMSS300 Safety Relay Manual

4.1 Dual channel emergency stop monitoring, manual reset, with EDM

Components:

1 dual channel emergency stop button (2NC)

1 reset button (NO)

2 contactors (with forced guiding NC contacts)

Wiring:

Power supply: A1 is connected to+24V, A2 is connected to 0V.

Test pulse: T1 is connected to emergency stop channel 1 NC input, T2 is connected to emergency stop channel 2 NC input. Connect NC to S1 and S2 respectively.

Reset/EDM: Connect the NC feedback contacts of two contactors in series, then connect them in series with the NO contact of the reset button, and finally connect them between X1 and A2.

Safe output: Three enable paths (13-14, 23-24, 33-34) are connected in series to the contactor coil circuit.

Work logic:

When the emergency stop is not pressed, both S1 and S2 are at high level (pulses from T1/T2).

Press the reset button and the feedback contact of the contactor is closed (i.e. the contactor has been disconnected), then the device is connected to the safety output and the contactor is closed.

Press the emergency stop button, and the safety output will immediately disconnect (≤ 12ms), causing the contactor to lose power.

If the contactor contacts are stuck, EDM will detect that the feedback contacts are not closed during the next start-up, prevent start-up, and report an error.

4.2 Protective door monitoring (single channel, automatic reset)

Applicable scenario: Non highest safety level, protective door switch is single NC.

Wiring:

T1 → Door switch NC in, NC out → S1. S2 is empty or short circuited to A2 (to ensure that the equipment can recognize single channel mode, the actual RLY3-EMSS300 supports single channel, but the security level has been lowered to Cat. 2).

Short circuit X1 to A2 (automatic reset).

Secure output connection actuator.

Attention: Single channel without cross circuit detection cannot detect wire short circuit faults and is only suitable for low-risk applications.

4.3 Two handed operation box (compliant with EN 574 Type IIIc)

Requirement: Both buttons must be pressed simultaneously within 0.5 seconds, and there must be no crossover circuit between them.

Wiring:

T1 → button 1 NO in, NO out → S1.

T2 → button 2 NO in, NO out → S2.

Do not use reset (automatic reset, as the dual hand operation box itself requires simultaneous pressing after each release).

Short circuit X1 to A2.

Safety output control press clutch, etc.

The built-in differential monitoring of the device (3 seconds) is sufficient for manual operation (0.5 second synchronization requirement). If stricter 0.5-second monitoring is required, external processing or the use of a dedicated dual hand control module is necessary.

Troubleshooting and Diagnosis

5.1 Meaning of LED indicator lights

The RLY3-EMSS300 panel is equipped with multiple LEDs for rapid diagnosis (the color and definition of each LED are not detailed in the data manual, but according to the rules of similar SICK products, they usually include):

PWR (green): The power supply is normal.

IN1/IN2: Safe input status (lit to indicate high input).

OUT: Safe output status (lit to indicate closed enable path).

ERR (red): Fault status (such as differential timeout, crossover circuit, EDM feedback error, etc.).

When ERR lights up, the device will lock the safety output until the fault is resolved and a reset is performed.

5.2 Common Fault Phenomena and Causes

Troubleshooting steps for possible causes of fault phenomena

After power on, the safety output cannot be connected, and the ERR constant light configuration is incorrect. If X1 is suspended or wired incorrectly, check whether X1 is wired correctly according to the required reset method (short circuit for automatic reset, button for manual reset, and button for normally open contact).

After pressing the reset button, the safety output is instantly connected and disconnected. If no feedback signal is received within the EDM time window, check whether the downstream contactor NC contact is closed. If the contactor coil has not been energized, the feedback contact should be closed (because the contactor is in an open state). Verify the wiring of the feedback loop.

The safety output sometimes does not respond, and the ERR flashing differential monitoring or crossover circuit detects intermittent faults. Check whether the contacts of the two safety input channels switch synchronously. Observe the T1/S1 and T2/S2 waveforms with an oscilloscope to see if there are any unexpected short circuits or open circuits.

When there is no fault, the safety output still cannot be connected. If the reset button is stuck or the normally open contact does not return normally, the voltage between X1 and A2 should be measured as 0V (automatic reset) or only jump to high level when pressed. If it remains high, the button will stick.

The emergency stop was not pressed but the safety output was disconnected. Internal self inspection revealed a fault, such as the failure of the output contact forced guiding mechanism to replace the equipment. Attention: Forced guiding contacts may experience mechanical jamming at the end of their lifecycle.

5.3 Response time verification

The nominal response time of the device (enable path disconnection) is ≤ 12 ms. This is the time from the disconnection of the safety input (such as the opening of the emergency stop contact) to the actual opening of the output contact. When designing a safe distance (such as the distance from a light curtain to a hazard source), engineers must accumulate this time with sensor response time, actuator action time, and controller delay.