[Incorrect data in from DigitalIn using pysdk]

Hi everyone,

Objective of the code: After confirming that the data is ready, the code reads the data from the specified channels. The goal is to identify changes in the signal, particularly detecting when there is a transition or edge change in the input.

Setup: The code configures a system to read digital inputs from two channels, DIO5 and DIO6.

Trigger Setup: It sets up a trigger mechanism, likely to start the data acquisition process when a specific condition (trigger) is met on the digital input.

Data Ready Check: It checks if the data is ready to be read. This is crucial to ensure that the system is prepared to provide meaningful information.

 

def counter(device_data, channel1,channel2, timout,counts,rpm):
    """
    Count the edge transitions on 2 channels

    parameters: - device data
                - selected DIO channel number
                - selected DIO channel number
                - duration of counter
                - return value of counts
                - calculated rpm value
    """

    sts = ctypes.c_byte()


    hzDI = ctypes.c_double()

    cSamples = 4096
    rgwSamples = (ctypes.c_uint16*cSamples)()
  
    current_time = datetime.now()

    # Print the current time
    print("Current System Time:", current_time)
    print("Waiting for acquisition...")
    while True:
        dwf.FDwfDigitalInStatus(device_data.handle, ctypes.c_int(1), ctypes.byref(sts))
        print(sts.value)
        if sts.value != None :
            break
        time.sleep(1)
    print("   done")

    # Get the current system time
    current_time = datetime.now()

    # Print the current time
    print("Current System Time:", current_time)                                                                 

    # get samples, byte size
    dwf.FDwfDigitalInStatusData(device_data.handle, rgwSamples, 2*cSamples)
    dwf.FDwfDeviceCloseAll()
    print(rgwSamples)

    # Extract dio1 (f1) and dio2 (f2) values
    dioa = [(sample >> channel1-1) for sample in rgwSamples]
    diob = [(sample >> channel2-1) for sample in rgwSamples]

    count = 0
    edge_indices_dio1, edge_samples_dio1 = find_edges_with_indices(dioa)
    edge_indices_dio2, edge_samples_dio2 = find_edges_with_indices(diob)
    for idx, sample in zip(edge_indices_dio1, edge_samples_dio1):
        print(f"DIO1 Edge at Sample {idx}, Value: {sample}")
        count = count +1
    for idx, sample in zip(edge_indices_dio2, edge_samples_dio2):
        print(f"DIO2 Edge at Sample {idx}, Value: {sample}")

    speeds_dio1 = calculate_speed(edge_indices_dio1, edge_samples_dio1, hzDI.value/100e6)
    speeds_dio2 = calculate_speed(edge_indices_dio2, edge_samples_dio2, hzDI.value/100e6)

    for i, speed in enumerate(speeds_dio1, start=1):
        print(f"DIO1 Speed between Edges {i} and {i+1}: {speed:.2f} units per second")

    for i, speed in enumerate(speeds_dio2, start=1):
        print(f"DIO2 Speed between Edges {i} and {i+1}: {speed:.2f} units per second")

    # time.sleep(100)

def find_edges_with_indices(dio):
    edge_indices = []  # List to store the indices of detected edges
    edge_samples = []  # List to store the sample values at edge transitions
    
    prev_sample = dio[0]  # Initialize with the first sample
    
    for i, sample in enumerate(dio[1:], start=1):
        if sample != prev_sample:
            edge_indices.append(i)
            edge_samples.append(sample)
        prev_sample = sample
    
    return edge_indices, edge_samples

def input_trigger_set(device_data,channel1,channel2):
    print("input_trigger set")
    set_mode(device_data=device_data,channel=channel1,output=True)
    # pull_direction = pull()
    # set_pull(device_data=device_data,channel=channel1, direction=pull_direction.idle)
    set_mode(device_data=device_data,channel=channel2,output=True)
    # set_pull(device_data=device_data,channel=channel2, direction=pull_direction.idle)

    sts = ctypes.c_byte()
    hzDI = ctypes.c_double()
    dwf.FDwfDigitalInInternalClockInfo(device_data.handle, ctypes.byref(hzDI))
    dwf.FDwfDigitalInDividerSet(device_data.handle, ctypes.c_int(int(hzDI.value/100e6))) # 100MHz

    # sample rate = system frequency / divider
    hzDI = ctypes.c_double()
    dwf.FDwfDigitalInInternalClockInfo(device_data.handle, ctypes.byref(hzDI))
    dwf.FDwfDigitalInDividerSet(device_data.handle, ctypes.c_int(int(hzDI.value/100e6))) # 100MHz
    # 16bit per sample format
    dwf.FDwfDigitalInSampleFormatSet(device_data.handle, ctypes.c_int(16))
    # set number of sample to acquire
    cSamples = 4096
    rgwSamples = (ctypes.c_uint16*cSamples)()
    dwf.FDwfDigitalInBufferSizeSet(device_data.handle, ctypes.c_int(cSamples))

    # Set trigger
    dwf.FDwfDigitalInTriggerSourceSet(device_data.handle,ctypes.c_int(3))
    dwf.FDwfDigitalInTriggerPositionSet(device_data.handle, ctypes.c_int(int(cSamples/10-1)))
    dwf.FDwfDigitalInTriggerSet(device_data.handle, ctypes.c_int(0), ctypes.c_int(0), ctypes.c_int(1<<channel1), ctypes.c_int(1<<channel1)) 

    # begin acquisition
    dwf.FDwfDigitalInConfigure(device_data.handle, ctypes.c_int(1), ctypes.c_int(1))

The data i get out 

dioa: [21, 29, 2926, 29, 21, 29, 2926, 29, 21, 29, 2926, 29, 21, 29, ...]

diob [10, 12, 1463, 12, 10, 12, 1463, 12, 10, 12, 1463, 12, 10, 12, ...]

 

what could be the problem?

 

 

[Multi channel pulse counter using py sdk]

Hi,

 

As the name suggests I am trying to develop a multi channel (DIO) pulse counter using the py WF_SDK. 

My application should count the quadrature pulses of a magnetic encoder within a given time frame and output the amount of positive and negative edges as well as the time from first edge transition till the last edge transition. Because the signal is quadrature, we need to capture the two signals simultaneously.

 

I'm not sure how this might be possible, TIA.

 

Thanks,

 

Ajay