Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules - Manual (Page 87)

Rockwell Automation Publication 1756-UM533C-EN-P - February 2011 87
1756-OF8H HART Analog Output Module Chapter 6
Module Fault Word Bits
Bits in this word provide the highest level of fault detection. A nonzero condition
in this word reveals that a fault exists on the module. You can examine further
down to isolate the fault.
Table 17 lists tags that are found in the Module Fault word.
Channel Fault Word Bits
During normal module operation, Channel Fault word bits are set if any of the
respective channels has a High or Low Limit Alarm or an Open Wire condition
(0…20 mA or 4…20 mA configurations only). When using the Channel Fault
Word, the 1756-OF8H module uses bits 0…7. Checking this word for a nonzero
condition is a quick way to check for these conditions on a channel.
Table 18 lists the conditions that set all Channel Fault word bits.
Your logic should monitor the Channel Fault bit for a particular output, if you
either enable output clamping, if you are checking for an open wire condition
(0…20 mA configuration only), or if you need to know if the output module is
not communicating with the controller.
Your logic can use the bit in Channel Faults, for example, Ch2Fault, to take
failure recovery action, such as signaling CVFault on a PIDE function block.
Table 17 - Tags Found in the Module Fault Word
Tag Description Tag Name
Analog Group Fault This bit is set when any bits in the Channel Fault
word are set. AnalogGroupFault
Calibrating This bit is set when any channel is being
calibrated. When this bit is set, all bits in the
Channel Fault word are set. Calibrating
Calibration Fault This bit is set when any of the individual
Channel Calibration Fault bits are set. CalFault
Table 18 - Conditions That Set All Channel Fault Word Bits
This Condition Sets All Channel Fault
Word Bits And Causes the Module to Display the
Following in the Channel Fault Word Bits
A channel is being calibrated 16#00FF
A communication fault occurred between
the module and its owner-controller 1#FFFF