Rockwell Automation 1771-OFE/B Analog Output Module User Manual User Manual

Page 44

4-8

Publication 1771Ć6.5.30 - November 1998

Figure 4.5

PLCĆ3 Example Program

FB001:0000

B0000

BTR

BLOCK XFER READ

Rack Address:

Group Address:

Module Address:

Data Address:

001

1 = High

FB003:0001

Length:

CNTL:

FB001:0000

CNTL

B0000

BTW

BLOCK XFER WRITE

Rack Address:

Group Address:

Module Address:

Data Address:

001

1 = High

FB002:0001

Length:

CNTL:

FB001:0000

CNTL

Rung Number RM0

Rung Number RM2

Rung Number RM3

Rung Number RM1

B0000

FB001:0000

Table 4.C

PLCĆ3 Data Table Word Assignments for Example 1

Start = FB002:0000

Word #

00000

0000

2048

1024

0150

0350

0100

0000

4095

00008

0000

4095

0020

0275

0100

0500

The PLC-5’s bidirectional program is very simple because the
processor handles the enable bits and ensures valid data. Two
examples are shown. The first is a write-only program you can use
when module status is not required. The second is a read/write
program.

Important: If the 1771-OFE module is configured in BCD data

format and you are using a PLC-5 processor, extra
programming will have to be added to the ladder
program (i.e. a CPT or TOD instruction) to convert
binary data to BCD data before it is transferred to the
1771-OFE module’s block transfer write data file. Also,
when checking your program’s operation, remember to
verify proper output voltage/current values based on the
data values sent to the module.

Block Transfer

Programming Ć PLCĆ5

Family Processors Only