Thomas1983

Hi @attila So sorry to bother you again, but from my message above, would you know why this discrepancy occurs?

Hi @attila Thank you for all your help. I just have one last question. I have an 8 channel multiplexer with channel 1 connected to the output and a function generator is sending a 2 kHz sine wave with a DC offset of 2.5 V to one of the inputs. I modified the code you provided and obtained the graph below (signals from mux, without looping). And I modified my code and obtained the graph below (signals from mux, with looping). My goal is to have the signals layered on top of each other (as seen in the “With Looping” graph) rather than appearing as a staircase. How can I fix my code in order to obtain a sine wave? Could it be an issue with my Trigger? (The legend indicates which DIO pins are on, I am using DIO1,2,3) ReadSignalsFrom8x1Mux_WithoutLooping.py ReadSignalsFrom8x1Mux_WithLooping.py

Hi @attila If I understand correctly, the 1000 samples I am collecting are being sampled at the specified rate of 100kHz. Does this mean that if I used my original perfcounter method correctly it would yield the same results? Additionally, Is there even a way to use the perfcounter method to timestamp each sample? When inputting the 1000 samples into the FDwfAnalogInStatus function. It seems to collect all the samples instantly and I am unsure how to get a timestamp (using perfcounter) for each interval. As a workaround, I resorted to inputting 1 sample at a time to get the timestamp and then using a for loop to iterate 1000 times.

Hi @attila I want to associate a real timestamp with each sample. While I understand the approach of using (start_time + j/hzAcq.value) to calculate timestamps, I am concerned about whether the samples are actually being collected at the specified rate or if this method is simply generating an arbitrary range of values. Can you clarify this? Thank you again for your help

Hi @attila Yes, I am doing that. However, instead of 8192 samples, I set it to 1 so I can associate a timestamp with each sample. I have included my Python file to provide more context. Thank you again for your help Additionally, I should mention this is what I am obtaining using Waveforms VoltageWithTimestamp.py

Hi @attila I have included the additional configuration, yet I am still encountering issues. Below is a graph generated by my Python script. I am observing unexpected "spikes" and irregular "longer/shorter" square wave-like features. I cannot seem to figure out why this is happening. Any insights would be greatly appreciated. edit: I forgot to mention that I am using an AD2

Hi @attila Thank you for the swift reply. I revamped my code and am now using “dwf.FdwfAnalogInStatusData”. However, I am still having issues obtaining the correct voltage values. Could the problem be that I am collecting only one sample and then looping it 1000 times? How can I fix this? Here is the revised code (I left every thing the same except my "acquire_samples" function and my printing loop: def acquire_samples(Channel1_samples, Channel2_samples): while True: dwf.FDwfAnalogInStatus(hdwf, c_int(1), byref(sts)) if sts.value == 2: break time.sleep(0.01) dwf.FDwfAnalogInStatusData(hdwf, 0, Channel1_samples, nSamples) # get channel 1 data dwf.FDwfAnalogInStatusData(hdwf, 1, Channel2_samples, nSamples) # get channel 2 data samples = (rgdSamples1_off, rgdSamples2_off) # Create file for writing file_name = 'Voltage.txt' with open(file_name, 'w') as f: for iteration in range(iterations): f.write("Timestamp, Channel 2, Channel 1\n") for j in range(1000): acquire_samples(*samples) start_time = time.perf_counter() sampleOff.append(rgdSamples1_off[0]) timestamp.append(start_time) f.write(f"{timestamp[j]}, {rgdSamples2_off[0]}, {rgdSamples1_off[0]}\n") print(f'Data successfully saved to {file_name}') dwf.FDwfAnalogOutReset(hdwf, c_int(0)) dwf.FDwfDeviceCloseAll()

I want to acquire 1000 samples and associate a timestamp with them, the way I am doing it is by collecting 1 sample and then using a loop to repeat the process 1000 times. Doing this I have no issue with the timestamp, however I am getting the wrong voltage values and I am not sure why. some additional info: I am sending a 2kHz square wave to channel 1 (from a function generator) that has a dc offset of 2.5 V and a 2kHz sine wave to channel 2 (from wavegen 1) and I am triggering off of channel 2 If anyone can help, it’ll be greatly appreciated! I have pasted my code below: # Declare ctype variables dwRead = c_uint32() hdwf = c_int() sts = c_byte() hzAcq = c_double(100000) # 100 kHz sampling rate nSamples = 1 timestamp = [] def OscilloscopeSet(): # Set up acquisition for both channels dwf.FDwfAnalogInBufferSizeSet(hdwf, c_int(nSamples)) dwf.FDwfAnalogInChannelEnableSet(hdwf, c_int(0), c_bool(True)) dwf.FDwfAnalogInChannelRangeSet(hdwf, c_int(0), c_double(10)) # Set the range to 10V dwf.FDwfAnalogInChannelEnableSet(hdwf, c_int(1), c_bool(True)) dwf.FDwfAnalogInChannelRangeSet(hdwf, c_int(1), c_double(10)) # Set the range to 10V dwf.FDwfAnalogInAcquisitionModeSet(hdwf, c_int(0)) # Acquisition mode dwf.FDwfAnalogInFrequencySet(hdwf, hzAcq) # Configure the signal generation dwf.FDwfAnalogOutNodeEnableSet(hdwf, c_int(0), c_int(0), c_bool(True)) dwf.FDwfAnalogOutNodeFunctionSet(hdwf, c_int(0), c_int(0), c_ubyte(1)) dwf.FDwfAnalogOutNodeFrequencySet(hdwf, c_int(0), c_int(0), c_double(2000)) dwf.FDwfAnalogOutNodeAmplitudeSet(hdwf, c_int(0), c_int(0), c_double(1)) dwf.FDwfAnalogOutOffsetSet(hdwf, c_int(0), c_double(2)) dwf.FDwfAnalogOutConfigure(hdwf, c_int(0), c_bool(True)) # Set up trigger dwf.FDwfAnalogInTriggerAutoTimeoutSet(hdwf, c_double(2)) # 2 second auto trigger timeout dwf.FDwfAnalogInTriggerSourceSet(hdwf, c_ubyte(2)) # trigsrcDetectorAnalogIn dwf.FDwfAnalogInTriggerTypeSet(hdwf, c_int(0)) # trigtypeEdge dwf.FDwfAnalogInTriggerChannelSet(hdwf, c_int(1)) # Channel 2 dwf.FDwfAnalogInTriggerLevelSet(hdwf, c_double(2)) # Trigger level set to 2V dwf.FDwfAnalogInTriggerHysteresisSet(hdwf, c_double(0.01)) # 0.01V dwf.FDwfAnalogInTriggerConditionSet(hdwf, c_int(0)) # trigcondRisingPositive dwf.FDwfAnalogInConfigure(hdwf, c_bool(False), c_bool(False)) # Acquisition mode # Wait at least 2 seconds for the offset to stabilize time.sleep(2) OscilloscopeSet() def acquire_samples(): time.sleep(0.01) dwf.FDwfAnalogInStatus(hdwf, False, None) channel1_samples = c_double() channel2_samples = c_double() dwf.FDwfAnalogInStatusSample(hdwf, c_int(0), byref(channel1_samples)) # get channel 1 data dwf.FDwfAnalogInStatusSample(hdwf, c_int(1), byref(channel2_samples)) # get channel 2 data return channel1_samples, channel2_samples # Create the file for writing file_name = 'Voltage.txt' with open(file_name, 'w') as f: f.write("Timestamp, Channel 2, Channel 1\n") for j in range(1000): print("test") channel1_value, channel2_value = acquire_samples() start_time = time.perf_counter() timestamp.append(start_time) f.write(f"{timestamp[j]}, {channel2_value}, {channel1_value}\n") print(f'Data successfully saved to {file_name}') dwf.FDwfAnalogOutReset(hdwf, c_int(0)) dwf.FDwfDeviceCloseAll()