I want to synchronize two PXI 6251 on a PXI 1000 chassis to acquire 32 analog inputs simultaneously. I am using python with the nidaqmx library. To do so, I want to export the sampling clock of one card on a digital output, route it to a digital input of the other and use it as an external clock. Is it a good strategy?
I have tried the following code. The analog input logging works, but I can't see the clock on the terminal 2.7 (PFI15)
import nidaqmx
import time
with nidaqmx.Task() as taskAI, nidaqmx.Task() as taskClkExport:
acquisition_time = 10
rateAI=50000
t=time.localtime()
file_path_2 = r'C:/Users/laboratorium/Documents/remi/{}_{}_{}_{}_{}_{}_slot2'.format(t.tm_year, t.tm_mon,t.tm_mday,t.tm_hour,t.tm_min,t.tm_sec)
# configure analog input task
for i in range(16):
taskAI.ai_channels.add_ai_voltage_chan("PXI1Slot2/ai{}".format(i))
taskAI.in_stream.configure_logging(file_path_2,
nidaqmx.constants.LoggingMode.LOG,
'myGroupName',
nidaqmx.constants.LoggingOperation.OPEN_OR_CREATE)
taskAI.timing.cfg_samp_clk_timing(rate=rateAI,
sample_mode=nidaqmx.constants.AcquisitionType.CONTINUOUS,
samps_per_chan=2048)
# configure clock exporting task
taskClkExport.do_channels.add_do_chan("PXI1Slot2/port2/line7")
taskClkExport.export_signals.export_signal(signal_id=nidaqmx.constants.Signal.SAMPLE_CLOCK,
output_terminal="PXI1Slot2/port2/line7")
print('start')
taskClkExport.start()
taskAI.start()
print('running...')
time.sleep(10)
print('stop')
taskAI.stop()
taskClkExport.stop()
I checked on MAX device routes, and any PFI is suited for direct routing of the sampling clock. I can invert the line from a DO task in MAX.
does someone knows the solution?
I could not export the sample clock on this gear, The solution I found is using the same master clock, and use the start trigger of the first card for the second one. I start the second one (waiting for the trigger) end then the first one.
self.task2.timing.ref_clk_src = "PXI_Clk10"
self.task2.timing.ref_clk_rate = 10000000
self.task2.timing.cfg_samp_clk_timing(rate=rate2,
sample_mode=nidaqmx.constants.AcquisitionType.CONTINUOUS,
samps_per_chan=2048)
self.task3.timing.ref_clk_src = "PXI_Clk10"
self.task3.timing.ref_clk_rate = 10000000
self.task3.timing.cfg_samp_clk_timing(rate=rate3,
sample_mode=nidaqmx.constants.AcquisitionType.CONTINUOUS,
samps_per_chan=2048)
self.task2.control(TaskMode.TASK_COMMIT)
self.task3.triggers.start_trigger.cfg_dig_edge_start_trig(
"/PXI1Slot2/ai/StartTrigger")
self.task3.start()
self.task2.start()