Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 74)

4–26 Planning an Application
Publication 2706-817
An ASCII Triggering device sends the [Ctrl-L] command to control
a tagged LED:
[Ctrl-L]LED #\LED State\MessageView Address[CR]
•
LED # is the LED being toggled
•
LED State is 1 (On) or 0 (Off)
•
MessageView Address is the node address of the terminal in the
ASCII network.
Handshaking is a means of acknowledging that a command has been
received and performed by either the MessageView terminal or the
logic controller.
The MessageView terminal supports handshaking for:
•
latched function keys
•
numeric and ASCII data entry variables
•
Auxiliary Port devices (hardware handshaking).
The MessageView terminal supports pseudo handshaking for:
•
momentary function keys
•
maintained function keys
•
acknowledge messages
•
all other messages.
Latched Function Key handshake
Latched Function Keys require a defined handshake tag. When a
message uses a Latched Function Key, the Function key write tag
notifies the logic controller that the Function key bit assigned is
latched in the On state. The controller then uses the handshake tag to
notify the MessageView terminal when the Function key is to be
unlatched.
The handshake tag for a Latched Function Key is globally defined in
the Function Key dialog. That is, the tag assigned to a Latched
Function Key is the same tag every time that Function key is enabled
for a message.
Handshaking