Publication 1769-UM002B-EN-P - July 2005
Module Data, Status, and Channel Configuration for the Output Modules 4-29
Open Wire Detection (1769-OF8C Only)
This feature detects when current flow is not present on an output channel
that is enabled and has a non-zero output value commanded.
When an open wire condition occurs channel, the diagnostic bit (D bit in
Input Data file status words) is set for that channel.
1769-OF8C and -OF8V Fault Mode (FM)
This configuration selection provides individual fault mode selection for the
analog channels. When this selection is disabled [the bit is reset (0)], the
module holds the last state, meaning that the analog output remains at the last
converted value prior to the condition that caused the control system to enter
the program mode.
If this selection is enabled [the bit is set (1)] and the system enters the program
mode, it commands the module to convert the user-specified value from the
channel’s Fault mode word to the appropriate analog output for the range
selected.
IMPORTANT
Hold last state is the default condition for the 1769-OF8C
and -OF8V during a control system run-to-program mode
change.
TIP
MicroLogix 1500™ does not support the analog output
module’s default hold last state function and resets analog
outputs to zero when the system enters the program mode.
TIP
Not all controllers support this function. Refer to your
controller’s user manual for details.
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