Rockwell Automation 1756-XXXX ControlLogix Digital I/O Modules - Manual (Page 46)

46 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Chapter 3 Common Module Features
Module Inhibiting
Module inhibiting lets you indefinitely suspend a connection between an
owner-controller and a digital I/O module without having to remove the module
from the configuration. This process lets you temporarily disable communication
to a module, such as to perform maintenance. You can use module inhibiting in
these ways:
• You write a configuration for an I/O module but inhibit the module to
prevent it from communicating with the owner-controller. In this case, the
owner does not establish a connection and the configuration is not sent to
the module until the connection is uninhibited.
• In your application, a controller already owns a module, has downloaded
the 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.
You may need to use module inhibiting in these instances:
• Multiple controllers own the same digital input module. A change is
required in the module’s configuration. However, the change must be
made to the program in all controllers. In this case, you follow these steps.
a. Inhibit the module.
b. Change configuration in all controllers.
c. Uninhibit the module.
• You want to upgrade a digital I/O module. We recommend you use this
procedure.
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, and you do not want the controller to continually look for a
module that does not yet exist. In this case, you can inhibit the module in
your program until it physically resides in the proper slot.
IMPORTANT Changing electronic keying selections online may cause the I/O
communication connection to the module to be disrupted and may result in a
loss of data.
IMPORTANT Whenever you inhibit an output module, it enters Program mode, and all
outputs change to the state configured for Program mode. For example, if an
output module is configured so that the state of the outputs transition to zero
during Program mode, whenever that module is inhibited, outputs transition
to zero.