Using a plc-2 with a sub i/o scanner, Block transfer example – Rockwell Automation 2705 RediPanel Push Button Module User Manual
Page 50
Chapter 4
Programming the RediPANEL Modules
4–11
When using a PLC-2 processor with RediPANEL module, the system must
contain a 1771-SN Sub I/O Scanner. Mini PLC-2 processors communicate
with remote I/O using this Sub I/O Scanner. The Sub I/O Scanner is located
in the same chassis as the mini PLC-2 and communicates with the PLC using
block transfers. The 1771-SN Sub I/O Scanner looks like an intelligent I/O
module to the PLC. You can also use Sub I/O Scanner in any chassis of a
PLC-2/20 or 2/30 system.
The 1771-SN requires one PLC scan to receive the output data from the
output image table and another PLC scan to send discrete input data to the
input image table. Anything connected to the Sub I/O Scanner is scanned
asynchronous to the PLC scan. The PLC then scans the Sub I/O Scanner
during the I/O portion of the PLC scan. See the section on Operating Cycles.
Block Transfer Example
Figure 4.2 shows an example of a block transfer between a Sub I/O Scanner
module and a PLC.
Figure 4.2
Block Transfer between Sub I/O Scanner and PLC–2
010
( EN )
17
Write information to the sub-scanner from PLC.
Read information from the sub-scanner into the PLC.
110
( DN )
17
BLOCK X-FER READ
DATA ADDR:
0030
MODULE ADDR:
101
BLOCK LENGTH:
014
FILE:
0200-0215
110
( DN )
16
010
( EN )
16
BLOCK X-FER WRITE
DATA ADDR:
0031
MODULE ADDR:
101
BLOCK LENGTH:
014
FILE:
0300-0315
Buffer the read information from the sub-scanner.
110
( DN )
16
010
( EN )
16
110
] [
17
FILE TO FILE MOVE
DATA ADDR:
0033
POSITION:
001
FILE LENGTH:
014
FILE A:
0200-0215
FILE R:
0400-0415
RAT PER SCAN:
014
1
2
3
Using a PLC-2
with a Sub I/O Scanner