Rockwell Automation 1756-DHRIO_DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module - Manual (Page 111)

Rockwell Automation Publication 1756-UM514C-EN-P - June 2014 111
Using the 1756-DHRIO and 1756-DHRIOXT Modules in Remote I/O Applications Chapter 9
Remote I/O Adapter
Failure Notification The speed at which the ControlLogix controller is notified that a remote I/O
adapter faulted is directly related to the RPI. The fault, known as a connection
timeout, occurs at four times the RPI. For example, if the RPI is set at 25 ms and a
fault occurs, the ControlLogix controller is not notified for 100 ms.
A remote I/O adapter fault notification occurs whenever the communication
between the remote I/O scanner (Channel A or B) and a remote I/O adapter is
interrupted or the communication between the 1756-DHRIO or
1756-DHRIOXT module and the ControlLogix controller is interrupted.
The Studio 5000 environment alerts you to a rack fault in at least one of the
following ways:
• nonzero condition in the Rack Status tag in the tag editor
• fault icon appears in the controller organizer
• connections page displays the fault type
Inhibit the Module
Connections When the inhibit bit is set for the 1756-DHRIO or 1756-DHRIOXT module,
the connection between the ControlLogix controller and the 1756-DHRIO or
1756-DHRIOXT module is terminated.
Although the 1756-DHRIO or 1756-DHRIOXT module connection is
inhibited, the DHRIO scanner (Channel A or B) changes to program mode and
continues to scan the remote I/O adapters on the remote I/O network. When
inhibited, a 1756-DHRIO or 1756-DHRIOXT module accepts configuration
from any ControlLogix controller in the control system.
The 1756-DHRIO or 1756-DHRIOXT module connection can be inhibited
on the module properties connection tab of the Studio 5000 environment.
Inhibit an Remote I/O
Connector Adapter When the inhibit bit is set for a remote I/O adapter connection, the connection
between the ControlLogix controller and the remote I/O adapter is terminated.
In this case, the 1756-DHRIO or 1756-DHRIOXT scanner (Channel A or B)
continues to scan the remote I/O rack on the remote I/O network and switches
the affected chassis of I/O into program mode. Only the ControlLogix controller
that initiated the configuration of the 1756-DHRIO or 1756-DHRIOXT
module can reestablish communication with the inhibited remote I/O adapter.
RIO rack connections can be inhibited on the module properties connection
dialog box of the Studio 5000 environment.