Is it possible to measure frequency using the counters while acquiring analog data using a multi-board PXI system?

[Brian0729]

I have written a VI, based on the counter examples, to acquire analog data and measure frequency. The master board triggers and drives the DAQ by routing its clock to the slave boards via RTSI lines. Based on the examples, I also routed the trigger and clock signals, that are available on the RTSI lines to the counters on the slave board. When I first ran the VI, it measured the frequency, however, it has not worked since. I am not sure if I have it wired wrong, or if the hardware won't allow it.

[markwysong]

Brian,

First, you need to tell people that the file you have included is a library (.llb file), because when I download it, it doesn't have an extension.

Next, I see where you have start the master board analog input acquisition, but I *don't* see where you have started the slave boards. You configure them, but you never start them, so they're not waiting for the trigger from the master.

I also don't see where you start your counters, either...they are configured (programmed), but never started.

Mark

[Filipe A.]

Brian;

I couldn't see where you routed the AI clock to the RTSI lines. That needs to happen before the counters get configured.

Regards
Filipe A.
Applications Engineer
National Instruments

[Brian0729]

Mark,

Sorry for the confusion. I have made the change to arm Counter 0. Also, here is a brief description of the VI: DAQ 3 Boards - State Machine - Scaled Array:

The VI is set up to collect data from 3 boards simultaneously. The master board drives the clocks for the slave boards and provides the trigger signal via RTSI. Here is a breakdown of its functions by case:

Case: Initialize Master Board
-This case initializes the acquisition for the master board and routes AI Scan Start to RTSI 0 and AI Start Trigger to RTSI 1.

Case: Initialize Slave Board...
-This case initializes the acquisition for the slave board. There is a case for each slave board. The clock is set to RTSI 0, the Trigger to RTSI 1, and the acquisition is started.


Case: Initialize Counter 0 on Slave #1
-This case initializes counter 0 on the first slave board to count the pulses on RTSI 0 and programs the counter.

Case: Initialize Counter 1 on Slave #1
-This case initializes counter 1 on the first slave board to look for a trigger on RTSI 1 and programs the counter.

Case: Start DAQ
-This case configures the trigger and clock for the master board and starts its acquisition. It also arms counter 1 on the first slave board.

Case: Start Counter 0
-This case starts the counter 0 on the first slave board.

I hope this helps make the VI more understandable.

Thanks,
Brian

[Brian0729]

I have detailed the function of the VI in a comment.

Thanks,
Brian