Rockwell Automation Publication 440R-UM013G-EN-P - December 2022 61
Chapter 11 Troubleshooting
Figure 67 - DI, DIS, and SI Safety Relay Pulse Test Waveforms
Effect of OSSD Test Pulses
GSR safety relays cannot detect short circuits of OSSD outputs. The PWR/Fault status indicator
of your GSR safety relay remains steady green. The device with the OSSD outputs must detect
short circuits of its own OSSD outputs. When detected, the device must shut off both OSSD
outputs and go to a faulted state. A status indicator must inform you that the OSSD is faulted.
See Devices with OSSD Output
on page 20 for more information.
Detect Off Pulses
When configured for monitored manual (or manual) reset, the GSR safety relay detects off
pulses as described in Table 16.
Test pulses on OSSD outputs are less than 1 ms; therefore the GSR safety 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 68 on page 62
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.
Table 16 - Off Pulses
Time Description
Off time ≥25 ms
GSR safety relays always detect when the input device turns off. GSR safety 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 safety relays turn off their output, but the
input does not turn back on. The input must be cycled again.
Off time < 7 ms GSR safety relays cannot detect inputs that turn off for 7 ms or less.
To Next Page
Loading...
Need help?
General
