Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 15)

Communicate with I/O modules Chapter 1
If module is And another controller And you want to Then use this type of connection
Owns the module ------------------------------------> Listen-only
There is a noted difference in controlling input modules versus controlling output
modules. The following table lists the differences.
Controlling This Ownership Description
Input modules Owner An input module is configured by a controller that establishes a connection as an owner. This configuring controller
is the first controller to establish an owner connection.
Once an input module has been configured (and owned by a controller), other controllers can establish owner
connections to that module. This lets additional owners to continue to receive multicast data if the original owner
controller breaks its connection to the module. All other additional owners must have the identical configuration
data and identical communications format that the original owner controller has; otherwise, the connection
attempt is rejected.
Listen-only Once an input module has been configured (and owned by a controller), other controllers can establish a listen-
only connection to that module. These controllers can receive multicast data while another controller owns the
module. If all owner controllers break their connections to the input module, all controllers with listen-only
connections no longer receive multicast data.
Output modules Owner An output module is configured by a controller that establishes a connection as an owner. Only one-owner
connection is allowed for an output module. If another controller attempts to establish an owner connection, the
connection attempt is rejected.
Listen-only Once an output module has been configured (and owned by one controller), other controllers can establish listen-
only connections to that module. These controllers can receive multicast data while another controller owns the
module. If the owner controller breaks its connection to the output module, all controllers with listen-only
connections no longer receive multicast data.
Electronic Keying is a feature that reduces the possibility that you use the wrong
device in a control system. When the wrong device is used, unexpected system
behavior can occur.
The Electronic Keying automatically compares the expected device, as defined in
your project, to the installed device. If keying fails, the controller does not establish
a connection to the device and a fault occurs on the device.
For each device in the project, the user-selected keying option determines if and
how an Electronic Keying check is performed. Three options are available:
• Compatible Module
• Disable Keying
• Exact Match
Carefully consider the benefits and implications of each keying option when
selecting between them. For some device types, fewer options are available.
Electronic Keying
Rock well Automati on Publication 1756- PM004E -EN-P - October 2014 15