User manual

138 Rockwell Automation Publication 1756-UM001O-EN-P - October 2014
Chapter 8 I/O Modules
• 1756 controllers
• 1756 ControlNet modules
• 1756 DeviceNet bridges
• 1756 EtherNet/IP modules
• 1756 I/O and speciality modules
• 1756-DHRIO
• 1756-DHRIOXT
Online Additions - ControlNet Considerations
ControlNet considerations that must be made depend upon the ControlLogix
ControlNet modules you are using.
1756-CNB and 1756-CNBR Modules
When you add I/O to the ControlNet network via the 1756-CNB or
1756-CNBR modules while online, these considerations must be made:
• Digital I/O modules can be added as rack-optimized connections if the
parent module is configured with rack-optimized connections.
• Digital I/O modules can also be added as direct connections.
• Analog I/O modules can be added only as direct connections.
• Disable the Change of State (COS) feature on digital input modules
because it can cause inputs to be sent more quickly than the RPI.
• If you plan to add large amounts of I/O to the ControlNet network,
dedicate one ControlNet network for I/O. For the dedicated
ControlNet network, verify that there is little or none of the following:
– HMI traffic
– MSG traffic
– Programming workstations
IMPORTANT
These ControlLogix modules cannot be added while online:
• Motion modules (1756-MO2AE, 1756-HYD02, 1756-MO2AS, 1756-MO3SE,
1756-MO8SE, 1756-MO8SEG, 1756-M16SE)
• 1756-RIO
• 1756-SYNCH
• 1756-56AMXN
TIP
While you can add a new digital I/O module to an existing rack-optimized
connection, you cannot add rack-optimized connections while online.