Rockwell Automation 1715-OF8I Redundant I/O System User Manual - Manual (Page 129)

Rockwell Automation Publication 1715-UM001C-EN-P - March 2014 129
Digital I/O Operation Chapter 3
• In your application, a controller already owns a module, has downloaded
configuration to the module and is currently exchanging data over the
connection between the devices. In this case, you can inhibit the module
and the owner-controller behaves as if the connection to the module does
not exist.
These examples are instances where you may need to use module inhibiting:
• You want to upgrade a digital I/O module. We recommend you do the
following.
a. Inhibit the module.
b. Perform the upgrade.
c. Uninhibit the module.
• You are using a program that includes a module that you do not physically
possess yet, but you do not want the controller to continually look for a
module that does not exist yet. In this case, you can inhibit the module in
your program until it physically resides in the proper slot.
Status Indicator Information
Each 1715 digital I/O module has a status indicator on the front of the module
that lets you check the module health and operational status of a module. The
status indicator displays vary for each module.
See Appendix A, 1715 Digital Input Module on page 246 , for detailed status
indicator information.
Features Specific to
1715-IB16D Digital Input
Modules
The features described in this section are available on 1715 digital input modules.
Data Transfer on Either Cyclic Time or Change of State
Digital input modules always send data at the RPI, but they send data only at a
change of state if the COS feature is enabled. COS is more efficient than RPI
because it multicasts data only when a change occurs.
IMPORTANT Whenever you inhibit an output module, it enters the Program mode and
all outputs change to the state configured for the Program mode. For
example, if an output module is configured so that the state of the outputs
go to zero (0) during Program mode, whenever that module is inhibited,
the outputs go to zero (0).