Rockwell Automation 1756-IF4FXOF2F ControlLogix High-speed Analog I/O Module - Manual (Page 48)

48 Rockwell Automation Publication 1756-UM005B-EN-P - January 2013
Chapter 3 Module Features
Clamping/Limiting
Clamping limits the data from an output so that it remains in a range configured
by the controller, even when the controller commands an output outside that
range. This safety feature sets a high clamp and a low clamp. Clamping alarms can
be disabled or latched on a per channel basis.
Once clamps are determined for a module, any data received from the controller
that exceeds those clamps sets an appropriate limit alarm and transitions the
output to that limit but not beyond the requested value.
For example, an application may set the high clamp on a module for 8V and the
low clamp for -8V. If a controller sends a value corresponding to 9V to the
module, the module only applies 8V to its screw terminals.
To see how to set the clamping limits, see page 78 .
Clamp/Limit Alarms
The Clamp/Limit Alarms feature works directly with clamping. When a module
receives a data value from the controller that exceeds clamping limits, it applies
the configured clamping limit value and sends a status bit to the controller
notifying it that the value sent exceeds the clamping limits (limit alarms).
For example, if a module has clamping limits of 8V and -8V but then receives data
to apply 9V, only 8V is applied to the screw terminals and the module sends a
status bit back to the controller informing it that the 9V value exceeds the
module’s clamping limits.
To see how to set the output alarms, see page 78 .
Output Data Echo
Output Data Echo automatically multicasts channel data values that represent
the analog signals applied to the module’s screw terminals at that time. Fault and
status data are also sent.