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Monitor/Control Reference Display for an Analog, RTD, or Thermocouple Block
For an analog, RTD, or Thermocouple block, the Monitor/Control Reference screen shows the current value for each circuit. For example:
M N T R (ckt. reference) | A | ||
I 2 : | ± 1 9 3 7 O |
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N O F A U L T S |
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> f o r c e r e l e s |
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For an analog block, the values may represent either engineering units or unscaled analog data.
For an RTD or Thermocouple block, the values represent tenths of degrees (Celsius or Fahrenheit), tenths of ohms, or unconverted counts.
Press F1 ( > ) to display other circuits.
Forcing an Analog, RTD, or Thermocouple Value
The HHM's circuit forcing capability must be enabled to perform this function.
1.Press F2 (Force) to force the displayed circuit.
2.If you make a mistake entering a value, use the Clear key to delete one digit at a time, starting with the last. To exit without forcing a circuit, press F2 (Change).
3.Press F3 (Enter) to save this value as the value for the circuit. The forced value will remain until you press F4 (reles), or enter a new value.
Diagnostics
Line 3 shows whether the circuit has any faults. If it does, one of these messages appears on line 3:
Feedback error: There is a wiring error or other hardware fault on a
High alarm/low alarm: An analog input value ex- ceeds its high or low alarm limit.
Input shorted: An RTD input circuit measurement is less than expected for the RTD type.
Internal fault: Internal calibration readings for a pair of RTD circuits are out of tolerance.
Open wire: On an RTD block, the RTD is missing or faulty, or there is an open wire. On an analog block, an input configured for 4 to 20mA has less than 2mA present.
Overrange/underrange: An analog or RTD circuit exceeds its maximum value.
Overtemperature: The block's internal tempera- ture exceeds 100_C.
Wiring error: There is a faulty connection be- tween an RTD and the block.
Clearing Circuit Faults
After correcting a fault condition, press the CLEAR key to remove the message and restore the reference to normal operation (the Clear Block Faults function must be enabled to use this feature). If the fault condition still exists, the fault message will reappear.