Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL User Manual
Page 105
5–16
Communications Overview
Publication 2706-817
Example: Discrete I/O
The MessageView 421 terminal occupies rack #3 in which its
starting module group is 0. The F1 key is addressed as I:030/03, and
the bit trigger for the next message as O:031/01.
➁ The PLC ladder program monitors address I:030/03.
Rack #3
MessageView I/O
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
8 Input Words
8 Output Words
030
031
➂ The operator presses F1. The terminal sets a bit in the
address assigned to that function key and clears the message.
➃ The ladder program reads bit 03 at address I:030/03.
030
031
Input Word
Output Word
➀ The MessageView monitors the status of
the 8 input words in its rack assignment.
➄ The ladder program sets bit 01 at address O:031/01.
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
03
01
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
➅ The terminal reads the address, which is assigned as a bit
trigger for the next message. The next message is displayed.