Rockwell Automation 1734-IA2, User Manual

Page: 116 / 242

Publication 1734-UM001D-EN-P - April 2008
114 POINT I/O Module Data
Since scalers have no restrictions, use care when configuring the module. If
the lower scaler is set to –32,768 and the module is in 4…20 mA (or
-10V…10V) mode, the module is incapable of setting the output to 0 mA (or
less than -10V on the 1734-OE2V module) because that requires a number
smaller than –32,768. –32,768 is the smallest number that you can represent
with a signed integer.
Fault and Idle/Program Mode Action
You can select what happens to the output if a fault occurs or if the module is
in Idle/Program mode. The choices are the following:
•
Hold Last State
•
Low Clamp
•
High Clamp
•
User defined value
The module default for both Fault and Idle/Program state is Low Clamp. All
values are scaled. You can set each action individually and on a per channel
basis. For an example of what would happen if the module lost
communication, see the table.
Channel Configuration When a fault occurs When module Is in Idle/program mode
Module Mode = 4…20 mA with
Scalers set at 0 and 8191 counts
Low Clamp = 0 counts
High Clamp = 8191 counts
Fault State = User Defined
Idle State = Low Clamp
Fault Value = 4095 counts
Channel 0 goes to 4095 counts
which equals 12 mA. Channel 0 goes to 0 counts which equals 4 mA.
Module Mode = 0…10V with
Scalers set at 0 and 10000 counts
Low Clamp = 0 counts
High Clamp = 10000 counts
Fault State = User Defined
Idle State = Low Clamp
Fault Value = 5000 counts Channel 0 goes to 5000 counts
which equals 5V. Channel 0 goes to 0 counts which equals 0V.