Allen-Bradley Guardmaster, User Manual

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Rockwell Automation Publication 440R-UM013E-EN-P - March 2017 71
Troubleshooting Chapter 11
detected, the device must shut off both OSSD outputs and go to a faulted state.
A status indicator must inform you that the OSSD device is faulted. See
Devices with OSSD Output on page 22 for more information.
Detect Off Pulses
When configured for monitored manual (or manual) reset, the GSR relay
detects off pulses as described in Table 15 .
Table 15 - Off Pulses
Test pulses on OSSD outputs are less than 1 ms; therefore the GSR relay
ignores the test pulses.
Capacitance Effect
Capacitance leakage of the input wiring to ground causes a deformation of the
leading edge of the pulses. Figure 66 shows the deformation with 1 µF on each
signal to ground. With this high capacitance, the CI safety relay still operates.
Capacitance from Ch1 to Ch2 looks the same as Ch1 to ground and Ch2
ground.
Figure 66 - Capacitive Effect on Pulse Tests
Time Description
Off time ≥25 ms GSR relays always detect the input device turning OFF. GSR relays also detect that the
input device has turned back ON.
7 ms < Off time < 25 ms When the off pulse is between 7…25 ms, GSR relays turn their output OFF, but the
input does not turn back ON. The input must be cycled again.
Off time <7 ms GSR relays cannot detect inputs that turn OFF for 7 ms or less.