The Isolated Input card's RTD and Thermocouple channels support full error detection for open loops and short circuits. MilliVolt and Voltage channels support partial error detection. For RTD and Thermocouple channels, use the channel Status parameter in DeltaV Diagnostics to diagnose errors. For MilliVolt and Voltage channels, use the Value and Status parameters to diagnose errors.
The following table lists how DeltaV Diagnostics reports short circuits and open loops in Isolated Input card channels.
| Channel type | Error condition | Value in DeltaV Diagnostics |
|---|---|---|
RTD – 2 Wire |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 |
Sensor Out of Range Sensor Out of Range; then Sensor Bad Sensor Out of Range; then Sensor Bad |
RTD – 3 Wire |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 Open Wire to Terminal 4 |
Sensor Out of Range Sensor Out of Range; then Open Sensor or A/D Converter error Sensor Out of Range Sensor Out of Range; then Open Sensor or A/D Converter error |
RTD – 4 Wire |
Short Open Wire to Terminal 1 Open Wire to Terminal 2 Open Wire to Terminal 3 Open Wire to Terminal 4 |
Sensor Out of Range Sensor Out of Range; then Open Sensor Sensor Out of Range Sensor Out of Range; then Open Sensor Sensor Out of Range |
Thermocouple |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 |
Shows the Cold Junction Compensation temperature. Value drifts upward; then goes out of range. Value drifts upward; then goes out of range. |
mV – Bipolar |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 |
Value is approximately 50%. Value is approximately 50%. Value is approximately 50%. |
Volts – Unipolar |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 |
Value near zero; Status may or may not be Bad. Value near zero; Status may or may not be Bad. Value near zero; Status may or may not be Bad. |
Volts – Bipolar |
Short Open Wire to Terminal 2 Open Wire to Terminal 3 |
Value is approximately 50%. Value is approximately 50%. Value is approximately 50%. |