Rockwell Automation 1769-OF4VI Compact I/O Isolated Analog Modules - Manual (Page 57)

Publication 1769-UM014B-EN-P - May 2010
Module Data, Status, and Channel Configuration for the Output Modules 4-5
1769-OF4CI and -OF4VI Under-Range Flag Bits (U0 to U3)
Word 1, bits 1, 5, 9, and 13 contain the under-range bits for channels 0 to 3.
When set (1), the under-range bit indicates that the controller is attempting to
drive the analog output below its normal operating range or below the
channel’s Low Clamp level (if clamp limits are set for the channel). However,
the module continues to convert analog output data to a minimum full range
value if clamp levels are not set for the channel.
If alarm latching is not enabled for the channel, the bit is automatically reset
(0) by the module when the under-range condition is cleared or the
commanded value no longer exceeds the low clamp (the output is commanded
to return to within the normal allowed range). The under-range bits apply to
all output ranges.
Refer to 1769-OF4CI Valid Output Data Table on page 4-17 and 1769-OF4VI
Valid Output Data Table on page 4-18 to view the normal operating and
under-range areas.
1769-OF4CI and -OF4VI Output Held Bits (H0 to H3)
Word 1, bits 2, 6, 10, and 14 contain the output held bits for input channels 0
to 3. When one of these bits is set (1), the corresponding channel is in the hold
state. Output data will not change until value commanded by the controller
matches the value being held by the module for any held output channel.
When the value commanded for a channel by the controller matches the value
being held by the module, the Output Held bit for that channel is cleared (0).
The output channel can again be directly controlled by the values commanded
in the Output Data file by the controller. The control can determine the
output value being held by the module for any channel whose Output Held bit
is set (1) by reading words 2 to 5 of the Input Data file.