Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 78)

4–30 Planning an Application
Publication 2706-817
Acknowledge messages pseudo handshake
The MessageView terminal supports a pseudo handshake for
acknowledgeable messages. The pseudo handshake uses the
Acknowledge Return Message Number tag defined in the Terminal
Setup Control Tags dialog. See Page 10–23.
If the Acknowledge Return Message Number tag is defined, the
MessageView terminal will return the message number associated
with a message each time an acknowledgeable message is
acknowledged. If a message is not acknowledged, no message
number is returned. This provides a means of signalling to the logic
controller that a message has been acknowledged.
The Acknowledge Return Message Number tag is globally defined.
That is, the Return Message Number tag address is the same for all
acknowledgeable messages.
All messages pseudo handshake
The MessageView terminal supports a pseudo handshake for all
messages not included in the above handshake types. The pseudo
handshake uses the Return Message Number tag defined in the
Terminal Setup Control Tags dialog. See Page 10–21.
If the Return Message Number tag is defined, the MessageView
terminal will return the message number associated with a message
that does not have the Ack attribute or function keys, each time the
message is displayed. If a message is not displayed, no message
number is returned. This provides a means of signalling to the logic
controller that a message has been displayed.
Note: Hidden messages do not return a message number when they
are processed, since they are not displayed.
The Return Message Number tag is globally defined. That is, the
Return Message Number tag address is the same for all messages.