Allen Bradley Guardmaster 440R Safety Relay Troubleshooting and Configuration Guide

Allen Bradley Guardmaster 440R Safety Relay Troubleshooting and Configuration Guide

Introduction: On site challenges of modular safety relays

In modern factory automation systems, safety relays are the core safety logic components that connect input devices such as emergency stop buttons, safety door switches, light curtains, safety carpets, and output actuators such as contactors and drivers. Guardmaster of Rockwell Automation ®  Safety Relay (GSR) series (including 440) R‑S13R2 CI、440R‑D22R2 DI、440R‑D22S2 DIS、440R‑EM4R2 EM、440R‑EM4R2D EMD  The 440R-S12R2 SI adopts a 22.5mm ultra-thin design, supporting single wire secure (SWS) communication, configurable logic (AND/OR), and pulse test diagnosis. For on-site maintenance engineers, quickly identifying LED flashing patterns, checking input/output wiring, and understanding timing functions are key to restoring safety circuits and reducing downtime.

This article combines the official user manual to provide an executable technical guide from six dimensions: hardware selection, wiring specifications, configuration process, LED diagnosis, common troubleshooting, and safety level requirements.

Model Overview and Selection Basis

The GSR series includes multiple models, and their input/output and main functions are compared as follows:

Model Catalog Number Safety Input Safety Output Auxiliary Output SWS Delay/Function

CI 440R-S13R2 1 channel dual channel 3 N.O. electromechanical 1 N.C. electromechanical only outputs none

SI 440R-S12R2 1 channel dual channel 2 N.O. electromechanical 1 PNP output only none

DI 440R-D22R2 2-channel dual channel 2 N.O. electromechanical 1 PNP input+output logic AND/OR

DIS 440R-D22S2 2-channel dual channel 4 PNP OSSD 1 PNP input+output logic AND/OR, high-capacity load output

EM 440R-EM4R2 only has SWS input 4 N.O. electromechanical 1 PNP input+output (direct) none

EMD 440R-EM4R2D SWS Input+B1/B2 4 N.O. Delay Electromechanical 1 PNP Input+Output Close Delay, Open Delay, Jogging

Selection Tips:

When expanding the number of output contacts, use EM or EMD as the slave station (connected to the host through SWS).

If delayed output (such as pressure relief behind a safety door) or jog function is required, EMD must be selected.

For capacitive loads such as the Safe Torque Off input of PowerFlex drives, it is recommended to use DIS 34/44 terminals (capable of withstanding 9 μ F capacitors).

CI/SI can directly replace the old MSR127/MSR126 models.

Installation and wiring points

3.1 Mechanical Installation

DIN rail: 35mm (EN 50022), directly clamped. Use a screwdriver to pry down the bottom latch during disassembly.

Spacing: Reserve at least 50.8mm ventilation distance above and below.

Shell protection: IP40 (NEMA 1), to be installed in control cabinets with IP54 or higher.

3.2 Terminal Wiring

All terminals are compatible with 0.2... 2.5 mm ² (24... 14 AWG) copper wire, with a torque of 0.4 N · m (4 lb · in). The terminal block is pluggable, and a small screwdriver can be inserted into the top slot to pry and remove it (refer to Figure 4 in the manual). Key terminal functions:

Terminal function

A1 24V DC power supply (+10%/-15%)

A2 24V common terminal

S11, S21 pulse test output (for mechanical contacts)

S12, S22 secure input channel 1/2 (first channel)

S32, S42 secure input channel 1/2 (second channel, only DI/DIS)

634 Reset/Monitor Input

L11 Single Wire Safety (SWS) Output

L12 Single Wire Safety (SWS) Input

Y32/X32 auxiliary output (PNP, conducting when safety output is disconnected)

13/14, 23/24... Safe output (N.O. or OSSD)

B1, B2 only EMD: jog input or can be triggered again to close delay input

3.3 Grounding Requirements

A 24V power supply certified by PELV or SELV must be used.

The 24V common terminal (A2) must be single point grounded to the protective ground (PE), otherwise it may cause false faults due to common mode noise (refer to Figure 61 in the manual).

If SELV is used and cannot be grounded, floating ground can be retained (but NFPA79 does not allow it).

Configuration Process (Five Step Method)

The GSR safety relay sets the logic, reset type, and delay through the front panel rotary switch. Before configuration, the input circuit must be closed (if the emergency stop button is not pressed).

Turn off the power and set the switch to position 0 (DI/DIS logic switch to 0); Set the CI/SI reset switch to 0; Set the Range and Time of EMD to 0, 1, or 10 respectively.

Power on: The PWR/Fault LED flashes red at 1Hz (indicating that the old configuration has been cleared and waiting for a new configuration).

Turn the switch to the desired position (refer to the table below).

Confirm configuration: The corresponding status LED will indicate the current switch position by the number of flashes (for example, if the LOGIC IN LED of EMD flashes 4 times, it indicates Time=4).

Power off and then power on: The new configuration is stored in EEPROM, and the device enters normal operation.

4.1 DI/DIS logic switch (10 levels, only used 1-8)

Position reset type logical expression

1. Manual monitoring (IN1 OR IN2) OR L12

2 Monitoring Manual (IN1 AND IN2) OR L12

3 Monitoring Manual (IN1 or IN2) AND L12

4 Monitoring Manual (IN1 AND IN2) AND L12

5 Automatic/Manual (IN1 OR IN2) OR L12

6 Automatic/Manual (IN1 AND IN2) OR L12

7 Automatic/Manual (IN1 or IN2) AND L12

8 Automatic/Manual (IN1 AND IN2) AND L12

Example: If two safety doors are connected in series and need to be closed simultaneously to reset, select position 4 or 8 (AND logic). If one of them is closed, choose OR logic.

4.2 CI/SI Reset Switch (3rd gear)

Location function

MM monitoring manual reset (requires rising edge+falling edge, pulse width 0.25... 3 seconds)

AM automatic/manual (when connected to 24V, it automatically resets; when connected to a button, it resets with a rising edge)

4.3 EMD Delay/Jogging Configuration (Range × Time)

Range switch: Select the function type (turn off delay, turn on delay, jog) and range (in conjunction with Time switch).

Time switch: If set to 1 at the beginning of the configuration, use a short range (such as 0.1... 10 seconds); If set to 10, use a long range (10... 3000 seconds).

Actual delay=Range reference value x (Time switch value x 10%).

For example: Range=3 (turn off delay, baseline 30 seconds), Time=5 → 30 × 50%=15 seconds.

Jogging function: It needs to be triggered when B1 is connected to 24V and L12 is ON. The ON time is the set value, and the OFF time is fixed at 500 ms.

Configuration precautions:

To make the shutdown delay retrievable, B1 and B2 must be short circuited before configuration.

If delay is required, B1 must be suspended.

After configuration is completed, the device must be powered off and saved within 5 minutes, otherwise it will permanently malfunction.

LED status diagnosis (quick reference)

5.1 Normal operation of LED

Meaning of LED color/status

PWR/Fault green is always on and normal

IN/IN1 green first input channel closed

IN2 green second input channel closed (DI/DIS)

LOGIC IN green SWS input L12 is ON

OUT green constant light safety output has been closed

OUT green flashing (1Hz) safety input closed, waiting for reset signal

B1 (EMD) green B1 input closed

LOGIC IN (EMD) flashing (1Hz) timing in progress (shutdown delay not yet expired)

LOGIC IN (EMD) fast flashing (8Hz) jog OFF time

5.2 Fault LED code (PWR/Fault indicator light)

Display status, fault types, possible causes, and solutions

The red light is constantly on and cannot be restored. The input or output is short circuited to 24V/0V, and there is an internal hardware error. Power off, restart, and reconfigure.

Red flashing (1Hz) configuration mode is normal, waiting for the switch to be set.

Red flashing twice (intermittent) configuration conflict. After power on, the switch position is inconsistent with the EEPROM. Reconfigure or check the switch.

Red flashes three times, B1-B2 connection error. After configuring EMD, B2 was short circuited to B1. Remove the short circuit and the fault will be automatically cleared.

Red flashing 4 times can trigger the input error EMD to non triggered mode, but L12 is turned on again during the shutdown delay period. Wait for the delay to end or reconfigure to trigger again.

Red flashing 5 times SWS fault L11/L12 signal abnormality, check wiring, shielding, and cable length (<30m).

The fault can be recovered by keeping the green light on and flashing the red light 4 times. If L12 flips more than once during the shutdown delay, it will automatically recover after the delay is over.

Common troubleshooting process (step-by-step)

Step 1: Check the PWR/Fault indicator light

Extinguish: No power supply. Check the A1/A2 voltage (should be 24V DC ± 15%).

Red flashing twice: The switch position does not match the stored value → Repeat the five step configuration.

Red flashing 4 times (under constant green background): see the table above.

Step 2: Check the power supply and grounding

Measure the voltage of A1-A2.

Confirm that the 24V common terminal is connected to the protective ground (only required for PELV). If the on-site grounding is poor and causes irregular faults, the grounding test can be temporarily disconnected (note: it is only for troubleshooting and must ultimately meet the standards).

Step 3: Check the security input

Measure the voltage between S11 and S21 and A2 using a multimeter. When the mechanical contact is disconnected, the S11/S21 of CI is about 19V; DI/DIS/SI is about 14V/18V (due to different pulse test waveforms).

After closing the contacts, the voltage of S12 and S22 should be close to the voltage of S11/S21. If the difference is greater than 2V, check the resistance or capacitance effect of the circuit.

Capacitive effect: Long line to ground capacitance will slow down the pulse front, but it can still work (for example, 1 μ F to ground can still operate).

Resistance effect: The total circuit resistance should be less than 900 Ω, and the round-trip of 22AWG wire within 200m is only about 21 Ω, which is rarely a problem.

OSSD device: Connect OSSD1/2 directly to S12/S22 and must share the same 24V reference. GSR cannot detect OSSD output short circuit, and upstream equipment needs to self diagnose.

Step 4: Check the SWS (Single Wire Safety) circuit

L11 output waveform: Send a set of pulses every 4ms (1ms+0.5ms), with a valid reading of 8-9V on the digital multimeter.

L12 input: LED LOGIC IN should light up. If it is not lit and L12 is not used, set the DI/DIS logic switch to 1, 2, 5, 6 (OR logic) to ignore L12.

SWS cable length ≤ 30m, it is recommended to use shielded wire. One L11 can drive up to 10 L12s.

Step 5: Check the reset circuit (S34)

If the OUT LED is flashing (waiting for reset), measure the voltage of A2 in connection with S3.

Automatic reset: S34 must be connected to 24V (constant high), and the safety output will immediately turn on after the input is closed.

Monitoring manual reset: S34 requires a pulse from 0V → 24V → 0V, and the low-level time must last for 0.25... 3 seconds. When using the button, the release time should be within this range.

External contact monitoring: The auxiliary contacts of the contactor can be connected in series in the S34 circuit. If the contacts are not closed, they cannot be reset.

Step 6: Check the safety output

Mechanical and Electrical Output (CI/DI/EM/EMD/SI): The output terminal is connected in series with the load. Confirm that the voltage of 13 or 23 is the same as the power supply, and the voltage of 14 or 24 is the same (when the output is ON). If the voltage is normal but the contactor does not engage, measure the contactor coil.

OSSD output (DIS): 14/24 terminal maximum load 1.5A, capacitance 1.6 μ F; The maximum load of terminal 34/44 is 0.5A, with a capacitance of 9 μ F. When the output is ON, the terminal voltage should be close to 24V. If connecting the PowerFlex driver S1/S2 input, it must be grounded together (the COM of the driver is connected to A2).

Auxiliary output: Y32 (DI/DIS/SI) and X32 (EM/EMD) conduct when the safety output is OFF (PNP output). If the safety output is OFF but the auxiliary output does not have 24V, it may be due to internal safety relay adhesion or internal failure, and the module needs to be replaced.

Step 7: EMD Special Input B1/B2

Jogging function: B1 is connected to 24V and L12 is ON → output ON for a set time and then OFF for 500ms.

Can trigger shutdown delay again: Short circuit B1-B2 before configuration. If L12 is turned on again during the shutdown delay period, the timer will be reset.

If the B1 LED lights up but has no waveform, it may be an internal fault.

Security level and maintenance recommendations

7.1 SIL/PL parameters

All GSR models meet the following requirements:

PFH: 1.5E-09~4.5E-09 (applicable to high demand mode)

SIL 3（IEC 61508 / IEC 62061）

Cat 4 / PLe（ISO 13849‑1）

MTTFd: ≥ 252 years

DCavg：98.8%

7.2 Service life and replacement

Electrical lifespan: 10 times of operation (electromechanical output).

After 20 years of use, replacement should be evaluated.

Online replacement: The GSR module supports hot swapping (can be replaced with power on, but must ensure that the safety circuit is disconnected).

7.3 Suggestions for spare parts

Common models: CI (440R-S13R2), DI (440R-D22R2), EM (440R-EM4R2).

Backup wiring terminal (pluggable, module can be replaced without disconnecting).

If using SWS, ensure that the cable length is ≤ 30m and prepare shielded cables.