Rockwell Automation T3431-CA ICS Regent Thermo Couple Input Assembly - Manual (Page 23)

Thermocouple Input Assembly (T3431)
P D - 6 0 2 4 M a r - 0 6
23
Maintenance
Calibration
The Mux contains an ultra-stable voltage reference circuit for
auto-calibration of all thermocouple channels. This circuit
does not require re-adjustment.
Cold junction sensors do not require re-adjustment.
Troubleshooting
The following procedure is used for troubleshooting the
thermocouple input. The only assumption made is that the
input module fault indicator is on.
1. If both the Mux and CJ indicators are off, replace the input
module.
2. If only the Mux indicator is on, check the termination
panel’s status indicators.
If either POWER indicator is off, verify that the
termination panel cable is connected and that the cable
connections at the I/O chassis are correct (refer to Figure
9). Replace the input module.
If the POWER indicators remain off, replace the Mux.
If both POWER indicators are on but the TX DATA
indicator is off, replace the Mux.
If both the POWER and TX DATA indicators are lit,
replace the Mux. If the Mux indicator is still on, replace
the input module.
3. If only the CJ indicator is on, check that the temperature
at the termination panel is between 0 ° and 60 ° C and that
there are no significant thermal gradients present.
Remove the Mux and check for damaged cold junction
sensors. The sensors are mounted to the termination
panel directly above the terminal block area.
If the sensors are not damaged, replace the Mux. If the CJ
indicator is still on, consult ICS for CJ sensor replacement
procedures and parts.