synchronizing digital output with analog data acquisition

[chrys]

I am attempting to synchronize digital output from an AT-MIO-16E-1 board with analog data acquisition. Basically all I need is to start the data acquisition at the same time the digital output goes out. Unfortunately, the examples provided with LabVIEW only pertain to DIO devices and also require external triggering (ideally, the whole task should be performed within the board, without any need for outside connections. I've managed to do this with analog output).
Does anyone have any idea as to how to address this problem?

thanks,
Jon.

[RobertoBozzolo]

If the analog side can be considered master, maybe you can try using Digital Trigger Config.vi (in the Advanced Digital I/O palette) in order to start digital output on some I/O connector input, and connect this input with ScartScan output (or other acquisition timing output you want) on the connector.

On the other side, if you must start acquiring when digital I/O starts, maybe you can play a while with AI Trigger Config.v in order to syncronize the two processes with the digital side mastering the other.

Sorry for generic response: I hadn't performed such task till now, but I'm now in trouble with syncronizing AI and AO and found a NI example that extensively use triggering instruments in order to syncronize the two processes, and I think this could apply to
your situation.

Roberto

[Murray Scott]

Jon, I had a similar problem synchronising motor steps with angle-dependant readings in a minimal-component application using a PCI-MIO-16E-4. I originally intended to use scaler outputs to drive the motor but could not change the step periods systematically to accelerate and decelerate the motor.

I did it by faking up a "TTL" signal using bufferred analog output. The AO UPDATE input pin was connected to the AI SCANCLK output, thus driving both processes from the internal AI pacer clock.

This is incredibly wasteful of memory, building large bufferfuls of 12bit analog data to fake up a logic signal, but it allowed nicely chirped acceleration and deceleration sequences and it did the job without missing a step. I imagine that in this way you could code whatever DO
signals you want and DI too if you use another AI channel.

[markwysong]

I would think that you could setup your data acquisition and configure it to use a digital trigger. Start it (it will be waiting for a trigger), and then perform the digital output when necessary. This should start the acquisition. I can show an example if you would like.

Mark

[chrys]

Mark, I would be grateful if you could show me an example.

thanks,
Jon.

[markwysong]

Try this VI. It sets up the data acquisition for a digital trigger. You will have to wrie the digital output which is to control the acquisition to PFI0.

Mark