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2 sample plc-5 ladder logic program – Rockwell Automation DeviceNet Communications Module User Manual

Page 55

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Using I/O Messaging

6-7

6.5.2 Sample PLC-5 Ladder Logic Program

Table 6.2 – Control File for Block Transfers

EN

ST DN ER CO EW NR TO RW RLEN DLEN FILE ELEM

R

G S

BT20:0

0

0

0

0

0

0

0

0

0

62

0

9

0

00

0

0

BT20:1

0

0

0

0

0

0

0

0

0

62

0

10

0

00

0

0

Figure 6.4 – Sample PLC-5 Ladder Logic Program

Sample PLC-5 program with an MD65 drive at DeviceNet node address 1.

The DeviceNet scanner gathers the drive status data via the network. The BTR in this rung
then moves the drive status data from the scanner to the N9: data file in the PLC, where:

N9:0 = Scanner Status word
N9:1 = MD65 (node 1) Logic Status
N9:2 = MD65 (node 1) Feedback

Note that the Feedback for the MD65 drive is received in Hz and not in engineering units.
For example, "300" equates to 30.0 Hz (the decimal point is always implied)
.

0000

BT20:0

EN

EN

DN

ER

BTR

Block Transfer Read
Module Type

1771-SDN DeviceNet Scanner Module

Rack

000

Group

0

Module

0

Control Block

BT20:0

Data File

N9:0

Length

62

Continuous

No

Setup Screen

BTR

This rung enables the DeviceNet scanner.

0001

N10:0

0

1771-SDN
Scanner
Enable bit