Need help to read out a simple resistance analog input value on my MCC USB-2404-UI DAQ.

[BenjaminF]

Hello,

I have downloaded all the required softwares to make the mcculw Python library to work.

Now i just need to read out the 10k 2w resistance value via channel 0 in Python.

How can this be done?

I get the value i want in InstaCal:

Br,

Benjamin

Edited November 28, 2023 by BenjaminF

[Fausto]

Hello @BenjaminF.

After confirming your device's configuration and measurements in InstaCal,

 

take a look at the MCC Universal Library Help.

 

The mcculw Python examples are saved to the 'C:\Users\Public\Documents\Measurement Computing\DAQ\Python\examples' directory on the target system.  Test the attached Python UI example, which was updated for your application.

ULAI15_27380_v1.py

Regards,

Fausto

 

[BenjaminF]

Hello @Fausto.

Thanks for answering me.

This was to good help, i can finally see a formatted resistance value, and not just the raw value.

But what i really need is to continuously read out a value from Channel 0 on the DAQ, as fast as it can sample. Also, i need this formatted to resistance.

I believe this is very easy task if you know what you are doing.

Do you have an example to do this?

I used your example and made this, which should print out the resistance value on python console.

from __future__ import absolute_import, division, print_function
from builtins import *  # @UnusedWildImport

from mcculw import ul
from mcculw.device_info import DaqDeviceInfo
from mcculw.enums import ScanOptions, ULRange, InfoType, BoardInfo, AiChanType

try:
    from console_examples_util import config_first_detected_device
except ImportError:
    from .console_examples_util import config_first_detected_device


def get_resistance():
    # By default, the example detects and displays all available devices and
    # selects the first device listed. Use the dev_id_list variable to filter
    # detected devices by device ID (see UL documentation for device IDs).
    # If use_device_detection is set to False, the board_num variable needs to
    # match the desired board number configured with Instacal.
    use_device_detection = True
    dev_id_list = []
    board_num = 0

    try:
        
        if use_device_detection:
            config_first_detected_device(board_num, dev_id_list)

        daq_dev_info = DaqDeviceInfo(board_num)
        if not daq_dev_info.supports_analog_input:
            raise Exception('Error: The DAQ device does not support '
                            'analog input')

        print('\nActive DAQ device: ', daq_dev_info.product_name, ' (',
              daq_dev_info.unique_id, ')\n', sep='')

        ai_info = daq_dev_info.get_ai_info()
        ai_range = ai_info.supported_ranges[0]
        channel = 0
        ul.set_config(InfoType.BOARDINFO, board_num, channel, BoardInfo.ADCHANTYPE,
                  AiChanType.RESISTANCE_10K2W)
        #value2 = ul.a_chan_input_mode(board_num, channel, ai_range)
        # Get a value from the device
        if ai_info.resolution <= 16:
            # Use the v_in method for devices with a resolution <= 16
            # (optional parameter omitted)
            value = ul.a_in(board_num, channel, ai_range)
        else:
            # Use the v_in_32 method for devices with a resolution > 16
            # (optional parameter omitted)
            value = ul.a_in_32(board_num, channel, ai_range)

        # Display the value
        print('Value:', value)
    except Exception as e:
        print('\n', e)
    finally:
        if use_device_detection:
            ul.release_daq_device(board_num)





if __name__ == '__main__':
    get_resistance()

(This code doesn't work, I get a raw value and not a formatted resistance value on the A/D)

I need to get this resistance value sampled every 0.1-1s for 30 seconds while im calibrating a sensor.

 

BR,

Benjamin

Edited November 30, 2023 by BenjaminF

[BenjaminF]

On 11/28/2023 at 7:51 PM, Fausto said:

Hello @BenjaminF.

After confirming your device's configuration and measurements in InstaCal,

 

take a look at the MCC Universal Library Help.

 

The mcculw Python examples are saved to the 'C:\Users\Public\Documents\Measurement Computing\DAQ\Python\examples' directory on the target system.  Test the attached Python UI example, which was updated for your application.

ULAI15_27380_v1.py 9.1 kB · 1 download

Regards,

Fausto

 

Dear @Fausto

My response:

Hello @Fausto.

Thanks for answering me.

This was to good help, i can finally see a formatted resistance value, and not just the raw value.

But what i really need is to continuously read out a value from Channel 0 on the DAQ, as fast as it can sample. Also, i need this formatted to resistance.

I believe this is very easy task if you know what you are doing.

Do you have an example to do this?

I used your example and made this, which should print out the resistance value on python console.

from __future__ import absolute_import, division, print_function
from builtins import *  # @UnusedWildImport

from mcculw import ul
from mcculw.device_info import DaqDeviceInfo
from mcculw.enums import ScanOptions, ULRange, InfoType, BoardInfo, AiChanType

try:
    from console_examples_util import config_first_detected_device
except ImportError:
    from .console_examples_util import config_first_detected_device


def get_resistance():
    # By default, the example detects and displays all available devices and
    # selects the first device listed. Use the dev_id_list variable to filter
    # detected devices by device ID (see UL documentation for device IDs).
    # If use_device_detection is set to False, the board_num variable needs to
    # match the desired board number configured with Instacal.
    use_device_detection = True
    dev_id_list = []
    board_num = 0

    try:
        
        if use_device_detection:
            config_first_detected_device(board_num, dev_id_list)

        daq_dev_info = DaqDeviceInfo(board_num)
        if not daq_dev_info.supports_analog_input:
            raise Exception('Error: The DAQ device does not support '
                            'analog input')

        print('\nActive DAQ device: ', daq_dev_info.product_name, ' (',
              daq_dev_info.unique_id, ')\n', sep='')

        ai_info = daq_dev_info.get_ai_info()
        ai_range = ai_info.supported_ranges[0]
        channel = 0
        ul.set_config(InfoType.BOARDINFO, board_num, channel, BoardInfo.ADCHANTYPE,
                  AiChanType.RESISTANCE_10K2W)
        #value2 = ul.a_chan_input_mode(board_num, channel, ai_range)
        # Get a value from the device
        if ai_info.resolution <= 16:
            # Use the v_in method for devices with a resolution <= 16
            # (optional parameter omitted)
            value = ul.a_in(board_num, channel, ai_range)
        else:
            # Use the v_in_32 method for devices with a resolution > 16
            # (optional parameter omitted)
            value = ul.a_in_32(board_num, channel, ai_range)

        # Display the value
        print('Value:', value)
    except Exception as e:
        print('\n', e)
    finally:
        if use_device_detection:
            ul.release_daq_device(board_num)





if __name__ == '__main__':
    get_resistance()

(This code doesn't work, I get a raw value and not a formatted resistance value on the A/D)

I need to get this resistance value sampled every 0.1-1s for 30 seconds while im calibrating a sensor.

 

BR,

Benjamin

[Fausto]

Hello @BenjaminF.

Please test the attached a_in_scan_background_27380_v1a.py example with your USB-2404-UI.

a_in_scan_background_27380_v1a.py

Regards,

Fausto

[BenjaminF]

Hi @Fausto,

I tried the code and it works.

But I really just want something even more simpler than this.

As mentioned im doing a calibration and need to get a live resistance reading while moving a stepper motor.

My only goal is:

1. Continuously read A/D value on channel 0 as fast as the serial communication can do

2. Format this to resistance and not this raw value.

3. Get this value when im asking for it to put it in the list when stepper motor is running

 

I'm actually confused to why this is'nt the 1st example on the GitHub:

imports.....

def read_ch0_value():
    - Continuously read A/D value on channel 0
    - Convert to resistance

def set_channel_settings(board_num):
    - set it to resistance and use in read_a_value

def get_ch0_value():
    - get the formatted resistance value when im asking for it

This is all i need.

Do i really have to use scan to get this simple value?

 

Edited December 1, 2023 by BenjaminF
Typo

[BenjaminF]

Hi @Fausto,

Is the solution i mentioned above possible?

 

I tried here, but the value that comes back to me is 0.00 and not the measured resistance. Why?

from mcculw import ul
from mcculw.enums import ScanOptions, FunctionType, Status, ULRange, InfoType, BoardInfo, AiChanType
from mcculw.ul import ULError
from mcculw.device_info import DaqDeviceInfo

board_num = 0
channel = 0
daq_dev_info = DaqDeviceInfo(board_num)
ai_info = daq_dev_info.get_ai_info()
ai_range = ai_info.supported_ranges[0]

def get_ohm_value():
    try:
        set_channel_settings(board_num)
        # Get a value from the device
        value = ul.a_in_32(board_num, channel, ai_range)
        # Convert the raw value to engineering units
        eng_units_value = ul.to_eng_units(board_num, ai_range, value)

        # Display the raw value
        print("Raw Value: " + str(value))
        # Display the engineering value
        print("Engineering Value: " + '{:.3f}'.format(eng_units_value))
        print(eng_units_value)
    except ULError as e:
        # Display the error
        print("A UL error occurred. Code: " + str(e.errorcode)
              + " Message: " + e.message)


def set_channel_settings(board_num):
    channel = 0
    # Set channel type to 10K 2W Resistance
    ul.set_config(InfoType.BOARDINFO, board_num, channel, BoardInfo.ADCHANTYPE,
                  AiChanType.RESISTANCE_10K2W)


get_ohm_value()

 

Edited December 5, 2023 by BenjaminF

[Fausto]

Hello @BenjaminF.

You need to use the a_in_scan() function, as I did in my previously attached example.

You can customize the code for your own application.  If you increase the sleep(), then you can slow the data display output.

Regards,

Fausto