Publication 1756-UM514B-EN-P - February 2003
8-14 Using the 1756-DHRIO Module in Remote I/O Applications
Adapter Module I/O Update Rate with the 1756-DHRIO Module in
the Local Chassis
When the 1756-DHRIO module resides in the same chassis as the
owner-controller, updated output data (refreshed to new values via
the control program) is delivered to the adapter module at:
RPI + scan rate per adapter * number of adapters
Where the RPI is equal to the value determined from the graphs on
page 10-6, and scan rate per adapter=3ms @ 230.4K, 5ms @115.2K, or
8ms @57.6K.
The updated input data is delivered to the ControlLogix controller at:
Scan rate per adapter * number of adapters
The update rate for an adapter module (i.e. the rate at which I/O data
is produced/consumed between the owner-controller and the
1756-DHRIO module) is:
RPI + 2[Scan rate per adapter * number of adapters]
This is a turnaround calculation for an output to input in the same
rack.
When you include block transfers, the update rate for an adapter
module is:
RPI + 2(Scan rate per adapter * number of adapters) + (Scan rate
per adapter * total number of adapters with BT modules in
them)
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