Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 111)

Transferring Discrete and BlockĆTransfer Data
Chapter 8
8-16
A PLC-5 processor, in scanner mode, transfers discrete-transfer and
block-transfer data with processor-resident local and remote I/O chassis. If
you have your processor configured for scanner mode, refer to the
following sections for more information on how a PLC-5 processor
transfers data in scanner mode. Also, the following sections provide
information on how to handle I/O rack faults for processor-resident local
and remote I/O (in scanner mode).
The processor scans processor-resident local I/O synchronously and
sequentially to the program scan.
The processor:
scans discrete-transfer data in the processor-resident local I/O chassis
synchronously and sequentially to the program scan.
scans discrete-transfer data in remote I/O chassis asynchronously to the
program scan. The remote I/O scan discrete-transfers I/O data between
remote I/O adapters in I/O chassis and the remote I/O buffer in the
processor.
performs housekeeping once per program scan: 3 ms maximum;
typically 1.5 ms
Transferring Data
Using Scanner Mode
Programming Discrete
Transfer in Scanner Mode
Read Inputs
Write Inputs
ProcessorĆ
Rack
I/O Image
Table
Resident
Data
Exchange
Housekeeping
Logic
Scan
Program Scan