Rockwell Automation RECOMM-DNET DeviceNet Adapter for use with DPI AC Drives - Manual (Page 77)

Using Explicit Messaging 7-11
Ladder Logic Program
Figure 7.8 – Sample PLC-5 Ladder Logic Program
0000
I:000
17
ONS
B3:0
0
EN
DN
ER
BTW
Block Transfer Write
Module Type 1771-SDN DeviceNet Scanner Module
Rack
000
Group 0
Module 0
Control Block BT20:2
Data File N30:0
Length 64
Continuous No
MOV
Move
Source
0
0<
Dest N30:70
257<
0001
BT20:2
DN
CMP
Comparison
Expression N30:70 <> N30:0
BT20:3
EN
EN
DN
ER
BTR
000
0
0
BT20:3
N30:70
64
No
0002 END
Block Transfer Read
Module Type 1771-SDN DeviceNet Scanner Module
Rack
Group
Module
Control Block
Data File
Length
Continuous
When I:000/17 is set to true, a one-time Block Transfer Write sends data to the scanner. The Move
instruction then initializes the first word of the data file that is used by the Block Transfer Read instruction in
the next rung.
When BT20:2.DN is true, the Block Transfer Write is complete. The
compare instruction compares the first word of data sent from the
scanner to the first word of data you send to the scanner. When the
messaging function is complete, the two words are equal.
If the Block Transfer Read is not enabled, this instruction enables it
when BT20:2.DN and the compare are true. The Block Transfer
Read reads 64 words of data.