Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 161)

7–40 Creating Messages
Publication 2706-817
While a message requiring acknowledgement is displayed, other
messages may not be displayed if they:
•
require an acknowledgement, or
•
contain entry variables.
Note: On a MessageView 421F terminal, a message with function
keys enabled may be displayed at the same time as a message
requiring acknowledgement.
!
ATTENTION: When using Remote I/O, if the
Acknowledge Message Return number global attribute
is enabled, assign the bit for the ACK key to the same
Block transfer block as the Acknowledge Message
Return number.
Bit Trigger
A Bit Trigger is optional, since a message can be triggered using its
Message Number. A Bit Trigger address must be unique, and a bit
address can be used to trigger only one message in the application.
Select the Enable check box to enable the Bit spin control. To edit
the number of the bit trigger:
•
select a value on the Bit spin control, or
•
highlight the current number, then type the correct bit address.
An application can have up to 1024 bit triggers if Block Transfers
are used, but the maximum number of bit triggers is much smaller if
only discrete I/O is used.
Note: In an application designed for use with an ASCII Triggering
device, bit triggers are not supported.
Triggering is discussed in the section starting on Page 4–9.