Rockwell Automation 1756-OF8I ControlLogix Eight-channel Isolated Analog I/O Modules - Manual (Page 97)

Rockwell Automation Publication 1756-UM540A-EN-P - May 2014 97
1756-OF8I Isolated Analog Output Module Chapter 5
Clamp/Limit Alarms
This function works directly with clamping. When a module receives a data value
from the controller that exceeds clamping limits, it applies signal values to the
clamping limit but also sends a status bit to the controller notifying it that the
value sent exceeds the clamping limits.
With the previous 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 where to set clamp and limit alarms, see page 133 .
Data Echo
Data Echo automatically multicasts channel data values that match the analog
value that was sent to the module’s screw terminals at that time.
The 1756-OF8I module returns a status word that represents the value sent to it
by the controller. The echoed value is indicated in input tag
I.Ch[x].Data and is
represented in Engineering Units.
Fault and status data are also sent. This data is sent at the RPI.