Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 162)

162 Publication 1756-UM009C-EN-P - December 2010
Chapter 7 Non-isolated Analog Output Modules (1756-OF4 and 1756-OF8)
Channel Status Words Bits – Floating Point Mode
Any of the Channel Status words (four words for 1756-OF4 and eight words
for 1756-OF8), one for each channel, will display a nonzero condition if that
particular channel has faulted for the conditions listed below. Some of these
bits set bits in other Fault words.
When the High or Low Limit Alarm bits (bits 1 and 0) in any of the words are
set, the appropriate bit is set in the Channel Fault word.
When the Calibration Fault bit (bit 4) is set in any of the words, the Calibration
Fault bit (bit 11) is set in the Module Fault word.
The table lists the conditions that set each of the word bits.
Tag (Status
word) Bit Event that sets this tag
ChxOpenWire Bit 7 This bit is set only if the configured Output Range is 0…20 mA, and the circuit
becomes open due to a wire falling or being cut when the output being driven
is above 0.1 mA. The bit will remain set until correct wiring is restored.
ChxNotaNumber Bit 5 This bit is set when the output value received from the controller is
NotANumber (the IEEE NAN value). The output channel will hold its last state.
ChxCalFault Bit 4 This bit is set when an error occurred when calibrating. This bit also sets the
appropriate bit in the Channel Fault word.
ChxInHold BIt 3 This bit is set when the output channel is currently holding. The bit resets
when the requested Run mode output value is within 0.1% of full-scale of the
current echo value.
ChxRampAlarm Bit 2 This bit is set when the output channel’s requested rate of change would
exceed the configured maximum ramp rate requested parameter. It remains
set until the output reaches its target value and ramping stops. If the bit is
latched, it will remain set until it is unlatched.
ChxLLimitAlarm Bit 1 This bit is set when the requested output value is beneath the configured low
limit value. It remains set until the requested output is above the low limit. If
the bit is latched, it will remain set until it is unlatched.
ChxHLimitAlarm Bit 0 This bit is set when the requested output value is above the configured high
limit value. It remains set until the requested output is below the high limit. If
the bit is latched, it will remain set until it is unlatched.
IMPORTANT
Notice that the 1756-OF4 and 1756-OF8 modules do not
use bit 6.