Publication 1756-UM514B-EN-P - February 2003
8-10 Using the 1756-DHRIO Module in Remote I/O Applications
Adapter Module I/O
The 1756-DHRIO module scans the remote I/O devices as they appear
in the ControlLogix controller’s controller organizer. The entries in the
organizer represent logical adapters. The physical adapter modules on
remote I/O may act as several racks. This depends on the addressing
mode of the physical adapter and chassis.
RSLogix 5000 allows 4 choices for the adapter modules:
· 1747 Remote I/O adapter
· 1771 Remote I/O adapter
· 1794 Remote I/O adapter
· Generic Remote I/O adapter
Each entry includes the following:
· rack address - values are 00-77 octal
· starting group - can start in slot 0, 2, 4, or 6
· rack size - can be 1/4, 1/2, 3/4 or full rack
The 1756-DHRIO module consumes the adapter output data sent by
the ControlLogix controller on the connection created when you add
remote I/O devices in RSLogix 5000.
The owner-controller produces the output data at the RPI; this output
data production is not tied to the scan time of the controller’s
program. The remote I/O scanner sends output data to the remote I/O
adapters at a rate dependent on the number of adapters on the
channel and the baud rate used.
The 1756-DHRIO module produces the rack input data received in the
adapter response immediately after the remote I/O adapter response
is received. The owner-controller receives the data directly into the
data buffer created by the software. The frequency at which the input
data is produced depends upon the number of adapters on the
channel and the baud rate used.
IMPORTANT
Each choice determines what type of adapter is
present on the remote I/O network. However, they
all behave the same in the ControlLogix system.
When online, the 1756-DHRIO module cannot tell
which specific adapter is connected to the remote
I/O network.
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