So I was successfully added a NI-9185 via Ethernet using the Python API. But when I trying to add channels (NI-9234 ai0:2 to read a tri-accelerometer), there is always issue with the channel name.
The current programming environment is Ubuntu, the same code can be run on the Windows machine. Is there something wrong with the way I am adding the channels?
I am attaching my code below (running on jupyter notebook) along with the error:
#################### this program is used to monitor the vibration data ########################################################
#################### the monitored data is saved into folder: x ############
#################### the monitored data is saved into small segments @ 1 second per segment ####################################
import nidaqmx
from nidaqmx.constants import AcquisitionType, ExcitationSource, AccelSensitivityUnits
import numpy as np
import time
from datetime import datetime
import os
ip="169.254.245.144" #169.254.62.190
device_name = "CNC_DAQ" # Optional, a name for the device
# Add the device, and attempt to reserve it
try:
added_device = nidaqmx.system.Device.add_network_device(ip, device_name=device_name, attempt_reservation=True)
except Exception as e:
print(f"Failed to add and reserve network device: {e}")
exit(1)
#Need to wait the device to be loaded
time.sleep(3)
print(f"Successfully added and reserved device: {added_device.name}")
print("The device IP:",ip)
channel = 'Mod1/ai0:2'
sample_rate = 51200
samples_to_acq = 51200 #51200
wait_time = samples_to_acq/sample_rate
# recording time
listening_time = 480
# specify IP instead to get the connection
cont_mode = AcquisitionType.CONTINUOUS
units_g = nidaqmx.constants.AccelUnits.G
all_data = []
#all_timestamps = []
i_flag = 0
#create folder if it is not there already
output_folder = r"C:\Users\NJAMI\DAQ_Vibration\Python_DAQ\Acquired data"
if not os.path.exists(output_folder):
os.makedirs(output_folder)
with nidaqmx.Task() as task:
print("Initilization data acquisition process")
# Create accelerometer channel and configure sample clock and trigger specs
task.ai_channels.add_ai_accel_chan(f"{added_device.name}{channel}", min_val=- 100.0, max_val=100.0, units=units_g,
sensitivity=50.0, sensitivity_units=nidaqmx.constants.AccelSensitivityUnits.MILLIVOLTS_PER_G,
current_excit_source=ExcitationSource.INTERNAL)#, current_excit_val=0.004)
task.timing.cfg_samp_clk_timing(sample_rate, sample_mode = cont_mode, samps_per_chan=samples_to_acq)
print("Reading DAQ...")
while True:
try:
# Reading data from sensor and generating time data with numpy
ydata = task.read(number_of_samples_per_channel=samples_to_acq)
#current_timestamp = datetime.now()
all_data.append(ydata)
#all_timestamps.append(current_timestamp)
i_flag += 1
## to save the data into small pieces
np.save(os.path.join(output_folder, f'accel_data_temp_{i_flag}.npy'), np.array(all_data)) # for save into smaller files
#np.save(os.path.join(output_folder, f'timestamps_temp_{i_flag}.npy'), np.array(all_timestamps)) # for save into smaller files
## to save the data into small pieces, comments out if not needed
all_data = []
#all_timestamps = []
# exit the monitoring after the number * wait time
if i_flag % listening_time == 0:
print("Data recorded with", sample_rate, "Hz sampling rate")
break
except KeyboardInterrupt:
print("Data acquisition stopped.")
try:
added_device.delete_network_device()
print(f"Successfully deleted network device: {added_device.name}")
except Exception as e:
print(f"Failed to delete network device: {e}")
the output and error:
Successfully added and reserved device: cDAQ9185-20FB3D9
The device IP: 169.254.245.144
reading starts
Initilization data acquisition process
---------------------------------------------------------------------------
DaqError Traceback (most recent call last)
<ipython-input-1-1cacad5452fa> in <module>
43 sensitivity=50.0,
44 sensitivity_units=nidaqmx.constants.AccelSensitivityUnits.M_VOLTS_PER_G,
---> 45 current_excit_source=ExcitationSource.INTERNAL)#, current_excit_val=0.004) 46 task.timing.cfg_samp_clk_timing(sample_rate, sample_mode = cont_mode, samps_per_chan=samples_to_acq)
47 print("Reading DAQ...")
~/.local/lib/python3.6/site-packages/nidaqmx/_task_modules/ai_channel_collection.py in add_ai_accel_chan(self, physical_channel, name_to_assign_to_channel, terminal_config, min_val, max_val, units, sensitivity, sensitivity_units, current_excit_source, current_excit_val, custom_scale_name)
211 sensitivity_units.value, current_excit_source.value,
212 current_excit_val, custom_scale_name)
--> 213 check_for_error(error_code)
214
215 return self._create_chan(physical_channel, name_to_assign_to_channel)
~/.local/lib/python3.6/site-packages/nidaqmx/errors.py in check_for_error(error_code)
125 cfunc(error_buffer, 2048)
126
--> 127 raise DaqError(error_buffer.value.decode("utf-8"), error_code)
128
129 elif error_code > 0:
DaqError: Physical channel specified does not exist on this device.
Refer to the documentation for channels available on this device.
Device: cDAQ9185-20FB3D9
Physical Channel Name: Mod0/ai0
Task Name: _unnamedTask<0>
Status Code: -200170
