National Instruments BridgeVIEW - Manual (Page 375)

Appendix A HMI Function Reference
© National Instruments Corporation A-55 BridgeVIEW User Manual
value timestamp returns the timestamp for when the tag value was
updated.
error indicates that an error occurred when executing the Read Tag VI, or
that the value output returned by Read Tag is not valid. See value status
for the specific error condition.
shutdown indicates that the BridgeVIEW Engine is shutting down. In this
case, the Read Tag VI no longer waits for tags to be updated and returns
immediately with both timeout and shutdown TRUE. You can use
shutdown to exit any loop that uses the Read Tag VI.
changed? is TRUE when the Read Tag VI returns a new value from the
Real-Time Database. If changed? is FALSE, the Read Tag VI probably
timed out before the tag value was updated.