Hi,
I'm creating a User Defined VI to be called from SignalExpress, that needs to poll a serial device for data.
The serial device makes new data availiable in a register-array at a rate of 10Hz, and uses an additional register as a "message ID" to indicate when new data is availiable.
This means that my VI needs to poll this MessageID, and when it increments, I can read the register array into a waveform and return it to SignalExpress.
Now, what is the best/correct way of writing this VI in regard to the polling wait time?
I see two options here for the case when my VI is called and it detects that no new message is availiable:
- It immediately returns to SignalExpress ("non blocking").
In this case, should I return an empty waveform or the previous waveform?
(I do not want duplicated data logged in SignalExpress)
- It blocks the SignalExpress loop where the user defined step is placed, by waiting in my VI until a new message arrives, and then returns this new data in a waveform.
My user defined step is placed in a separate loop in signal express so the blocking in case 2 should not affect other DAQ loops in my SignalExpress project, right?
/LeifS
