Figure 1.9, Figure 1.10 – Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM User Manual

Page 36

Publication AG-UM008C-EN-P - February 2005

1-18 Designing Communication

Figure 1.9

DF1 Radio Communication

Figure 1.10

Read or Write Requests via DF1 Radio Modem

Modem

Station 2

Station 1

2. Station 1 sends its reply message.

1. Message (via MSG instruction) sent to a specific

station (eg., station 1).

•

Send command
packet

•

Start reply
timer

•

Wait for reply
(or timeout)

•

Ladder logic
triggers MSG

•

DF1 driver
formats
command
packet

Data table

reply timeout received
return error indication

reply packet received return data