Rockwell Automation 1771-IL/B , D17716.5.91 ISOLATED ANALOG INPUT Module - Manual (Page 23)

Communicating With Your Module
Chapter 3
3-4
The PLC-5 program is very similar to the PLC-3 program with the
following exceptions:
1. Block transfer enable bits are used instead of done bits as the
conditions on each rung.
2. Separate block transfer control files are used for the block transfer
instructions.
Figure 3.3
PLC-5 Family Sample Program Structure
BTR Enable
EN
DN
Pushbutton
Power–up Bit
BTW Enable Bit
1
2
Bit
ER
EN
DN
ER
BTR
BLOCK TRANSFER READ
RACK:
GROUP:
MODULE:
DATA FILE:
LENGTH:
CONTINUOUS:
N
BTW
BLOCK TRANSFER WRITE
RACK:
GROUP:
MODULE:
LENGTH:
CONTINUOUS:
N
X
X
X
XXX:XX
00
X
X
X
00
Thereafter, the program continuously reads
data from the module (rung 1). A subsequent
BTW operation is enabled by a pushbutton
switch (rung 2). Changing the processor
mode will not initiate a block transfer write.
At power-up, the program enables a block
transfer read (rung 1). Then it examines the
power-up bit in the BTR file and initiates one
block transfer write to configure the module
(rung 2).
Program Action
CONTROL: XXX:XX
DATA FILE: XXX:XX
CONTROL: XXX:XX
PLC-5 Programming