SICK RLY3-EMSS300 Safety Relay Manual

Rated impulse withstand voltage Uimp: compliant with Class III

Response time (enable path disconnection): ≤ 12 ms (time from safety input disconnection to output contact opening)

2-channel application diagnostic output (Y1, Y2)

Type: Push pull semiconductor output, short circuit protection, non safety related

High level: ≥ V_s -3 V

Low level: ≤ 3 V

Output current capability: ≤ 120 mA (PNP), fill current ≤ 15 mA (NPN mode)

Purpose: Can be connected to PLC or indicator lights, used to display device status (such as safety output ON/OFF, faults, etc.)

Functional Configuration and Wiring Guide

All functions of RLY3-EMSS300 are configured through hard wired terminal connections without the need for software. The following is a typical method for setting up functions.

3.1 Reset Type Selection

The device supports two reset methods:

Automatic reset: When the safety input circuit is closed and the external device monitoring (EDM) conditions are met, the safety output is automatically restored. Suitable for situations where operator confirmation is not required (such as leaving after briefly entering an object in a light curtain protection area).

Manual reset: After the safety input is closed, the reset button (instantaneous contact) still needs to be pressed for the safety output to be connected. This is the standard requirement for most emergency stop and protective door applications to prevent accidental restarts.

Wiring method:

Manual reset: Connect the normally open contact of the reset button between terminals X1 and A2 (0V).

Automatic reset: Connect terminal X1 directly to A2 (short circuit).

Note: In manual reset mode, the device will monitor whether the pressing time of the reset button is within the valid range (usually 0.15 s to 2 s, but the data manual does not provide specific values, refer to the experience of similar devices). If the button gets stuck, the system will not start.

3.2 External Device Monitoring (EDM)

External device monitoring is used to detect whether downstream contactors or relays are disconnected as expected (i.e. feedback the status of the contacts). After the safety output is disconnected, the EDM input must detect the NC contact closure (or NO contact disconnection) of the downstream actuator within the specified time, otherwise the system will report an error and prohibit the next start.

When EDM is enabled:

Connect the forced guide NC contacts of the downstream contactor in series and connect them between X1 and A2.

At the same time, the reset button must not be connected to X1 again, as X1 is reused as an EDM input.

If EDM and manual reset need to be used simultaneously, the reset button must be connected in series with the EDM contact through external logic and connected to X1 (but the device itself does not support two independent functions and requires an external relay extension).

In RLY3-EMSS300, the X1 terminal is used for both reset and EDM, and cannot be used simultaneously. If the application requires EDM+manual reset, it is recommended to use other models of SICK or external circuits.

3.3 Differential monitoring and cross circuit detection

For dual channel safety sensors (such as emergency stop buttons with two NC contacts connected in series), the device is equipped with:

Differential monitoring: detect the time difference between two channels when switching states. If the difference time exceeds 3 seconds (for the reset button) or a specific set value, the device will enter a fault state.

Cross circuit detection: By testing the pulse output (T1/T2) to provide pulse signals of different phases to two channels, when the signals of the two channels are accidentally short circuited, the equipment recognizes a cross circuit fault and disconnects the safety output.

Wiring method (dual channel NC with cross circuit detection):

Connect T1 to the common terminal of the first NC contact and lead it from the normally closed terminal of the contact to the safety input S1.

Connect T2 to the common terminal of the second NC contact and lead it from the normally closed terminal of the contact to the safety input S2.

S1 and S2 are internally connected to logic, and the device automatically compares the two pulse signals.

If cross circuit detection is not required (for example, if the sensor already has fault monitoring, such as a type 4 light curtain), two NC contacts can be connected in series to S1 and A2 (single channel), but this can only reach Cat.2/PL c level.

3.4 Testing Pulse Output Usage

Three test pulse outputs (T1, T2, T3) can be used to power external sensors and achieve line monitoring. Each test pulse outputs a pulse sequence with a width of 2 ms and an interval of 40 ms. Attention: The test pulse output cannot directly drive high current loads and is only suitable for sensors or small relay coils.

Wiring rules:

Dual channel sensor: T1 → Channel 1 → S1, T2 → Channel 2 → S2.

Single channel sensor: T1 → sensor → S1, S2 short circuited to A2 or empty (dual channel monitoring needs to be turned off in the parameters, but hard wired devices have no parameters and need to be implemented through wiring).

Typical Application Circuit Example