Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 66)

4–18 Planning an Application
Publication 2706-817
A MessageView 421D terminal without a daughterboard (Catalog
No. 2607-M1D only) is a Slave Device. MessageView 421D Slave
Devices are shipped with an application downloaded. The
application provides the ASCII characters and graphics needed to
display messages.
The MessageView 421D Slave Device terminal does not support a
Startup or Background message. It acts as a “dumb terminal”, which
can receive data but not transmit it. It can accept commands from a
variety of slaving (master) devices. A list of master devices is given
on Page 5–8.
A message is displayed as soon as it is received from the master
device. There is no buffering or Message Queue. If a message is
received that is slated for a line which has another message
displayed, the old message is terminated at once and the new
message is displayed.
Embedded variables are treated as follows:
•
Display, time and date variables in slaved messages are displayed
by the 421D Slave Device. They are updated by the Master
Device as long as they are displayed.
•
ASCII Characters are displayed.
•
Graphics may be displayed if the Ctrl-G control code is inserted.
The slave packet format and control codes are given on Page 7–42.
Slave Device