Hi everyone,
I am trying to read in multiple pulse inputs simultaneously using the nidaqmx library in Python, and I'm having some trouble. My physical setup consists of the following:
DAQ: NI-cDAQ-9178
Module: NI-9411 (Digital Input)
I know there isn't a lot of great documentation for using the nidaqmx library with python but I don't believe I'm attempting anything too complicated and I'm hopeful that someone can identify the error in my ways. For context, I'm essentially trying to use the NI-9411 as a counter for continuous edge detection. I've been able to successfully create a task that reads in pulses from an external signal generator. The problem however comes when I try to create multiple tasks (i.e. read from multiple channels). I have attempted to configure a separate task for each of the four channels and have used the add_ci_count_edges_chan() method to configure each task for edge counting. I am then attempting to continuously read the counts from each channel in a loop using the ci_count property. The result is that Channels 1 and 2 seem to work fine and read their corresponding pulses, however 3, and 4 just seem to be duplicating the read from channel 2. Here is an example of my code:
import nidaqmx
import nidaqmx.system
from nidaqmx.constants import Edge
import time
system = nidaqmx.system.System.local()
# ci Channel names where system.devices[2] = cDAQ1Mod2
cDaq = system.devices[2].name
ci_chan1 = system.devices[2].ci_physical_chans[0].name
ci_chan2 = system.devices[2].ci_physical_chans[1].name
ci_chan3 = system.devices[2].ci_physical_chans[2].name
ci_chan4 = system.devices[2].ci_physical_chans[3].name
# Define the input channels and tasks
task1 = nidaqmx.Task("task1")
# Configure the task for edge counting
task1.ci_channels.add_ci_count_edges_chan(counter=ci_chan1,
name_to_assign_to_channel="",
edge=nidaqmx.constants.Edge.RISING,
initial_count=0)
task2 = nidaqmx.Task("task2")
# Configure the task for edge counting
task2.ci_channels.add_ci_count_edges_chan(counter=ci_chan2,
name_to_assign_to_channel="",
edge=nidaqmx.constants.Edge.RISING,
initial_count=0)
task3 = nidaqmx.Task("task3")
# Configure the task for edge counting
task3.ci_channels.add_ci_count_edges_chan(counter=ci_chan3,
name_to_assign_to_channel="",
edge=nidaqmx.constants.Edge.RISING,
initial_count=0)
task4 = nidaqmx.Task("task4")
# Configure the task for edge counting
task4.ci_channels.add_ci_count_edges_chan(counter=ci_chan4,
name_to_assign_to_channel="",
edge=nidaqmx.constants.Edge.RISING,
initial_count=0)
# Start the task
task1.start()
task2.start()
task3.start()
task4.start()
try:
while True:
count1 = task1.ci_channels[0].ci_count
count2 = task2.ci_channels[0].ci_count
count3 = task3.ci_channels[0].ci_count
count4 = task4.ci_channels[0].ci_count
print("Count 1: {}, Count 2: {}, Count 3: {}, Count 4: {}".format(count1, count2, count3, count4))
time.sleep(1)
except KeyboardInterrupt:
pass
finally:
# Stop and clear the tasks
task1.stop()
task1.close()
task2.stop()
task2.close()
task3.stop()
task3.close()
task4.stop()
task4.close()
Any help or advice would be greatly appreciated. Thanks in advance!