Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 75)

4–27 Planning an Application
Publication 2706-817
Numeric and ASCII Data Entry handshake
Numeric and ASCII data entry variables do not require a defined
handshake tag. However if you want to enable the handshake feature
of a data entry variable message, both a notification tag and a
handshake tag must be defined.
•
When a notification tag is assigned, the MessageView terminal
has a means of signalling that data entered from the terminal has
been transferred to the logic controller.
•
When a handshake tag is assigned, the logic controller has a
means of signalling the MessageView terminal that it received the
data.
Note: Define both notification and handshake tag or neither. If only
one is defined, the application will not pass validation.
Note: If a message contains more than one data entry variable, each
variable is supported by its own write tag address. However the
notification and handshake tags are shared by all data entry variables
in the message. Consider the write tag to be local to the individual
data entry variable, and the notification and handshake tags global to
the message as a whole.
Example:
Message A contains:
Enter Air Temperature: XXX; Enter Water Temperature: YYY.
where XXX and YYY are data entry variables.
If XXX is assigned these tag addresses:
Write Tag Address: TAG_A
Notification Tag address: TAG_NOTIFY
Handshake Tag Address: TAG_HAND
Then YYY would be assigned these tag addresses:
Write Tag Address (any tag address but TAG_A)
Notification Tag Address TAG_NOTIFY
Handshake Tag Address TAG_HAND
If the notification or handshake tag is changed in one of the data
entry variables in a message, the change affects all data entry
variables in that message.