How The Scanner Interacts With Adapters - Allen-Bradley 1747-SN User Manual

1–6 Overview
How the Scanner Interacts
with Adapters
Processor
SLC Local Chassis
Publication 1747 6.6 - July 1996
The scanner's function is to continuously scan the adapters on the
RIO link in a consecutive manner. This scan consists of one or more
RIO discrete transfers to each adapter on the RIO link.
RIO discrete transfers consist of the scanner sending output image
data and communication commands to the adapter that instruct the
adapter on how to control its output. (These include run, adapter
reset, and reset decide commands.) The adapter responds by sending
input data to the scanner. The scanner performs as many RIO
discrete transfers as necessary to update the entire adapter image. If
RIO discrete transfers do not occur, data is not exchanged between
the scanner and adapter. RIO discrete transfers are asynchronous to
the processor scan.
Scanner
RIO Discrete
Transfers
RIO Discrete
Transfers
RIO Discrete
Transfers
with Adapter 1
with Adapter 2
with Adapter 3
RIO Discrete
Transfers
with Adapter 4
PanelView Operator
Terminal
RediPANEL