Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 161)

Publication 1756-UM009C-EN-P - December 2010 161
Non-isolated Analog Output Modules (1756-OF4 and 1756-OF8) Chapter 7
Module Fault Word Bits – Floating Point Mode
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.
The table lists tags that are found in the Module Fault Word.
Channel Fault Word Bits – Floating Point Mode
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 configuration only). When using the Channel Fault
Word, the 1756-OF4 module uses bits 0…3, and the 1756-OF8 uses bits 0…7.
Checking this word for a nonzero condition is a quick way to check for these
conditions on a channel.
The table 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.
• are checking for a open wire condition (0 …20 mA configuration only).
Tag Description
Analog Group
Fault This bit is set when any bits in the Channel Fault word are set. Its tag
name is 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. Its tag name is
Calibrating.
Calibration Fault This bit is set when any of the individual Channel Calibration Fault bits
are set. Its tag name is CalibrationFault.
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 ‘000F’ for all bits on the 1756-OF4 module
‘00FF’ for all bits on the 1756-OF8 module
A communications fault occurred
between the module and its
owner-controller ‘FFFF’ for all bits on either module