National Instruments BridgeVIEW 用户手册
Appendix A
HMI Function Reference
© National Instruments Corporation
A-65
Write Tag (discrete)
Use the Write Tag (discrete) VI to update the Real-Time Database with a new value for
memory, output, and Input/Output tags. The value also is sent to the server if it is an output
or Input/Output tag. If the tag is an input only tag, the Write Tag (discrete) VI causes a system
error because input tags only can be updated by servers. If the tag is configured as an
Input/Output tag, the tag value is passed to the server when Write Tag (discrete) VI is called
but not written to the RTDB. The RTDB is updated with the new value when the server polls
it and passes it back to the BridgeVIEW Engine. This maintains correct time synchronization
in the RTDB.
memory, output, and Input/Output tags. The value also is sent to the server if it is an output
or Input/Output tag. If the tag is an input only tag, the Write Tag (discrete) VI causes a system
error because input tags only can be updated by servers. If the tag is configured as an
Input/Output tag, the tag value is passed to the server when Write Tag (discrete) VI is called
but not written to the RTDB. The RTDB is updated with the new value when the server polls
it and passes it back to the BridgeVIEW Engine. This maintains correct time synchronization
in the RTDB.
tag name is the name of the output tag.
value is the value written to the output tag.
generate event (F) determines whether a user change event is generated
for the write operation on the tag. If the tag is configured with event logging
on, this tag event can be displayed in the Event History Display in your
HMI and logged to a .
for the write operation on the tag. If the tag is configured with event logging
on, this tag event can be displayed in the Event History Display in your
HMI and logged to a .
evt
file. By default, generate event is FALSE.
status returns the current status of the value written in the Real-Time
Database. If status is greater than or equal to 0, the Write Tag (discrete)
operation was successful. If status is less than 0, either the device server
has reported an error indicating there is a problem with the tag, or
BridgeVIEW has reported an error indicating there is a problem using
the tag.
Database. If status is greater than or equal to 0, the Write Tag (discrete)
operation was successful. If status is less than 0, either the device server
has reported an error indicating there is a problem with the tag, or
BridgeVIEW has reported an error indicating there is a problem using
the tag.
error indicates that an error occurred when executing the Write Tag
(discrete) VI, or that the status of the tag is bad. See status for the specific
error condition.
(discrete) VI, or that the status of the tag is bad. See status for the specific
error condition.
shutdown indicates that the BridgeVIEW Engine is shutting down. You
can use shutdown to exit any loop that uses the Write Tag (discrete) VI.
can use shutdown to exit any loop that uses the Write Tag (discrete) VI.