Synchornizing analog output and a digital output

[ranibar]

Hi,

I am using python to generate analog signals. 

In addition to two analog signals that I am generating I want to generate a digital signal which should start at each cycle of the analog signal. I searched a lot for an answer

seems that the way to go is to specify the same clock for the analog and the digital tasks. however I don't know how to specify the clock for the digital output, while my analog outputs clock are just the internal clock.

Thank you

[ranibar]

I am trying to set the clock source of the analog task and the digital task to the same clock. the clock that I am trying to use is the counter (Ctr0) but when I am trying to configure the clock source of the tasks to 'Ctr0InternalOutput' I am getting an error that this property is not supported. Am I calling it wrong? 

Can somebody advice please

[croohcifer]

Please do the following:

1. Post a simple code example that produces the error
2. Post a screenshot of the error
3. Let us know which DAQ device you're using

[ranibar · Accepted solution]

Thank you croohcifer for you reply.

I eventually solved this. I will, however, since this is opened already, post a complete specification of hardware and the solution.

I am using a PXIe-1073 chassis with a PXI-6733 which is connected to a BNC-2110. 

I wanted to make a digital signal from ao0 to be emitted simultaneously with a digital signal port0/line0; i.e. make them use the same clock. 

The solution was simple, but somehow it was difficult to find the naming convention of the clock.

I will post the code that I am using:

#imports

import nidaqmx
from nidaqmx import stream_writers

#channels rates

sampling_rate = 20000
samples_per_chan = 500

#define signals

signal_square = np.append(np.ones(20), np.zeros(480))

T = 10*[True]
F = 490*[False]
digital = T + F

#define tasks

analog_output = nidaqmx.Task()
digital_output = nidaqmx.Task()

analog_output.ao_channels.add_ao_voltage_chan('PXI1Slot4/ao0')

analog_output.timing.cfg_samp_clk_timing(rate=20000, sample_mode=nidaqmx.constants.AcquisitionType.CONTINUOUS, samps_per_chan = 500)

writer = stream_writers.AnalogSingleChannelWriter(analog_output.out_stream, auto_start=False)

digital_output.do_channels.add_do_chan('PXI1Slot4/port0/line0')
digital_output.timing.cfg_samp_clk_timing(rate=20000, source='ao/SampleClock', sample_mode=nidaqmx.constants.AcquisitionType.CONTINUOUS, samps_per_chan=500)

#writing commands

writer.write_many_sample(signals, False)
digital_output.write(digital, False)

#Start

digital_output.start()
analog_output.start()

note that two things are important here: first "auto_start=False", and secondly start the digital_output task before the analog_output task. 

what I was missing is the name of the source of the digital clock ('ao/SampleClock')