AB Quality ALLEN-BRADLEY 1791 User Manual page 53

PLC 5 and PLC-5/250
Program Example
Program Action
At power up, the program enables a block
transfer read. Then, it initiates one block
transfer write to configure the module (rung 2).
Thereafter, the program continuously does
block reads and writes.
This program is very similar to the PLC-3 program with the following
exceptions:
Use enable bits instead of done bits as the conditions on each rung.
Use separate control files for each block transfer instruction. Refer to
Appendix B.
Figure 6.2
PLC 5 Family Sample Program Structure
BTR Enable BTW Enable
N7:0 N7:5
1
15 15
BTR
BTW
Enable
Enable
N7:0 N7:5
2
15 15
BTR
BTW
Enable
Enable
N7:0 N7:5
3
15 15
Chapter 6
Programming Your Analog Module
BTR
BLOCK XFER READ
RACK:
GROUP:
MODULE:
CONTROL:
DATA FILE:
LENGTH:
CONTINUOUS:
PU
BTW
BLOCK XFER WRITE
N10:0
RACK:
GROUP:
15
MODULE:
CONTROL:
DATA FILE:
LENGTH:
CONTINUOUS:
PU
BTW
N10:0
BLOCK XFER WRITE
RACK:
15
GROUP:
MODULE:
CONTROL:
DATA FILE:
LENGTH:
CONTINUOUS:
EN
1
0
DN
0
N7:0
ER
N10:0
5
N
EN
1
0
DN
0
N7:5
ER
N10:10
27
N
EN
1
0
DN
0
N7:10
ER
N10:10
3
N
6-3