Rockwell Automation 2706-M1 MESSAGEVIEW 421 HARDWARE MANUAL - Manual (Page 74)

4–14 Running Applications
Publication 2706–816
A slave terminal has no processing ability. When the master device
sends it a message, the slave displays it at once. If another message
arrives that is assigned to the same display line, the slave terminates
the previous message and displays the new one.
Every MV421D terminal (Catalog Number 2706–M1D) intended as
a slave device is shipped with a blank application. The application
supports the text fonts and graphics required to display the messages
sent by the master device.
The following Allen–Bradley products may be used as a master
device slaving to a MessageView 421D terminal Slave Device:
•
Dataliner

DL20
•
Dataliner

DL40
•
MessageView 421D terminal with Daughterboard card
•
MessageView 421N terminal with Daughterboard card
•
MessageView 421F terminal with Daughterboard card
•
PanelView

550
•
PanelView

900
•
PLC

•
SLC

Slave Packet format
The MessageView terminal supports transmission of messages to a
slave device, using Simplex protocol.
The Simplex protocol consists of a data packet with 6 data fields:
Field Field 1 Field 2 Field 3 Field 4 Field 5 Field 6
Contents
Optional
Control
Byte
ASCII Text
and special
Control
Characters
Optional
Display
Mode Byte
Slave
Address Line
Number
Carriage
Return
(CR]
Number
of Bytes
1 0 to 100 1 1 1 1
Note: Simplex protocol is compatible with Allen-Bradley DL20,
DL40, DL50 and MessageView 421D slave devices.
Slave Device