Table of Contents
Chapter 11
Troubleshooting
68
2. Check the voltage at each of the inputs with the device contacts closed,
as shown in
Figure
measured at terminals S11 and S21.
a. If both channels are closed, a voltmeter must read about 19V and the
IN indicator is green. The voltage levels are approximately the same
on Channel 1 (S12) and Channel 2 (S22) because the pulse testing
waveforms are similar on both channels.
b. If only one input is above the turn ON voltage level, then the IN
indicator is red.
c. Try cycling the input device.
d. If the contacts of the safety device do not operate consistently, the
safety device must be replaced.
Figure 61 - Check the CI Safety Inputs with the Device Contacts Closed
DMM
19
Volts
3. If a significant difference in voltage levels exists, see
on page 71
and
To find where the voltage drop is occurring, you have to trace the wiring
of the circuit that is not achieving at least 11V as measured by an
oscilloscope.
Check DI, DIS, and SI Safety Relays
DI, DIS, and SI safety relays can also be checked in a similar fashion. The
voltage of Channel 1 is lower (about 14V) than Channel 2 (about 18V). The
reason for the difference in voltage levels is due to the difference in the pulse
test wave forms (see
Figure 65 on page
than S21.
Rockwell Automation Publication 440R-UM013E-EN-P - March 2017
61. The values must be very close to the values
S21
S22
S12
S11
Pulse Testing
A2
Outputs
Long Wire — Resistance Effect on page
70). S11 is effectively OFF longer
DMM
19
Volts
Capacitance Effect
72.
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