Analog discovery 2 settling time and maximum record length

[Thomas Lee]

Hi,

I am developing a system including the wavegen, digital out triggers and oscilloscope based on the analog discover 2 and programmed with the SDK python.

The codes are shown as attached, currently the codes works well but I have three questions:

1. nSamples = int(8192), the datasheet shows the maximum record length is 16 k, however, when I increase the nSample to any value over 8192, the records went wrong. Since there are two analogIn channels, is that means the maximum record length for each channel is 8 k?

2. The time.sleep =3s issue, the python examples say the oscilloscope need 2 s to stabilize, I am wondering what is the minimum time interval between each time AnalogIn oscilloscope sampling? Since my application requires 500 times oscilloscope capture, decreasing the time interval helps a lot.

3. Currently I used one AnalogIn channel, and I am trying to use two AnalogIn channels and each channel triggered with rising edge of different digital out signal. However, I found that it seems like the two channels are triggered with only the first detected rising edge of the two trigger signals. I am wondering is there any solution to apply the two seperate triggers for the two oscillisope channels?

 

Thanks!

Zeyu

hdwf = c_int()
sts = c_byte()
hzAcq = c_double(5e6)
nSamples = int(8192)
cAvailable = c_int()
cLost = c_int()
cCorrupted = c_int()
fLost = 0
fCorrupted = 0

#print(DWF version
version = create_string_buffer(16)
dwf.FDwfGetVersion(version)
print("DWF Version: "+str(version.value))

#open device
for j in range(1,50, 1):

  print("Opening first device")
  dwf.FDwfDeviceOpen(c_int(-1), byref(hdwf))
  rgSamples1 = (c_int16*nSamples)()
  if hdwf.value == hdwfNone.value:
      szerr = create_string_buffer(512)
      dwf.FDwfGetLastErrorMsg(szerr)

      print(str(szerr.value))
      print("failed to open device")
      quit()

  print("Generating sine wave...")

  #  dwf.FDwfDigitalOutTriggerSourceSet(hdwf,c_int(0), c_int(8))
#  dwf.FDwfDigitalOutTriggerSourceSet(hdwf,c_int(1), c_int(8))
  dwf.FDwfDigitalOutDividerSet(hdwf, c_int(0), c_int(20))
  dwf.FDwfDigitalOutDividerSet(hdwf, c_int(1), c_int(20))
  dwf.FDwfDigitalOutDividerSet(hdwf, c_int(2), c_int(20))   
  dwf.FDwfDigitalOutDividerSet(hdwf, c_int(3), c_int(20)) 
#  dwf.FDwfDigitalOutDividerSet(hdwf, c_int(4), c_int(20))
  dwf.FDwfDigitalOutCounterInitSet(hdwf, c_int(0), c_uint(0), c_uint(1))
  dwf.FDwfDigitalOutCounterInitSet(hdwf, c_int(1), c_uint(1), c_uint(1))
  dwf.FDwfDigitalOutCounterInitSet(hdwf, c_int(2), c_uint(0), c_uint(1))
  dwf.FDwfDigitalOutCounterInitSet(hdwf, c_int(3), c_uint(1), c_uint(1))
#  dwf.FDwfDigitalOutCounterInitSet(hdwf, c_int(4), c_uint(1), c_uint(1))

  dwf.FDwfDigitalOutEnableSet(hdwf, c_int(0), c_int(1))
#  dwf.FDwfDigitalOutRunSet(hdwf, c_double(0.00005)) # 1ms run
#  dwf.FDwfDigitalOutWaitSet(hdwf, c_double(0)) # 1ms run
#  dwf.FDwfDigitalOutRepeatSet(hdwf, c_int(3))
  dwf.FDwfDigitalOutCounterSet(hdwf, c_int(0), c_uint(4150), c_uint(27150)) # 100MHz base freq /(30+30) = 1.67 MHz
  dwf.FDwfDigitalOutEnableSet(hdwf, c_int(1), c_int(1))
  dwf.FDwfDigitalOutCounterSet(hdwf, c_int(1), c_uint(27050), c_uint(4250)) # 100MHz base freq /(30+30) = 1.67 MHz
#  dwf.FDwfDigitalOutRunSet(hdwf, c_double(0.00005)) # 1ms run
#  dwf.FDwfDigitalOutWaitSet(hdwf, c_double(0)) # 1ms run
#  dwf.FDwfDigitalOutRepeatSet(hdwf, c_int(3)) # once
  dwf.FDwfDigitalOutEnableSet(hdwf, c_int(2), c_int(1))
  dwf.FDwfDigitalOutCounterSet(hdwf, c_int(2), c_uint(28350), c_uint(2950)) 
  dwf.FDwfDigitalOutEnableSet(hdwf, c_int(3), c_int(1))
  dwf.FDwfDigitalOutCounterSet(hdwf, c_int(3), c_uint(27300), c_uint(4000))
#  dwf.FDwfDigitalOutEnableSet(hdwf, c_int(4), c_int(1))
#  dwf.FDwfDigitalOutCounterSet(hdwf, c_int(4), c_uint(27300), c_uint(4000))

  dwf.FDwfAnalogOutTriggerSourceSet(hdwf,c_int(0),c_int(12))
#  dwf.FDwfAnalogOutTriggerSlopeSet(hdwf,c_int(0), DwfTriggerSlopeRise)
# dwf.FDwfAnalogInTriggerChannelSet(hdwf, 1) # 1st channel
#  dwf.FDwfAnalogOutTriggerLevelSet(hdwf, c_double(0.5)) # 0.5V

  dwf.FDwfAnalogOutNodeEnableSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_bool(True))
  dwf.FDwfAnalogOutNodeFunctionSet(hdwf, c_int(0), AnalogOutNodeCarrier, funcSine)
  dwf.FDwfAnalogOutNodeFrequencySet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double((16.8+j/50.000)*hzAcq.value/500.000))
  dwf.FDwfAnalogOutNodeAmplitudeSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(5)) 
  dwf.FDwfAnalogOutRunSet(hdwf,c_int(0), c_double(270000/(hzAcq.value*10))) # run for 2 periods
#  dwf.FDwfAnalogOutWaitSet(hdwf, c_int(0), c_double(10000/hzAcq.value)) # wait one pulse time
  dwf.FDwfAnalogOutRepeatSet(hdwf, c_int(0), c_int(1)) # repeat 5 times  

  dwf.FDwfAnalogInChannelEnableSet(hdwf, c_int(0), c_bool(True))
  dwf.FDwfAnalogInChannelRangeSet(hdwf, c_int(0), c_double(5))
  dwf.FDwfAnalogInAcquisitionModeSet(hdwf, acqmodeRecord)
  dwf.FDwfAnalogInFrequencySet(hdwf, hzAcq) 
  dwf.FDwfAnalogInRecordLengthSet(hdwf, c_double(nSamples/hzAcq.value)) # -1 infinite record lengt 

  dwf.FDwfAnalogInTriggerAutoTimeoutSet(hdwf, c_double(0)) #disable auto trigger
  dwf.FDwfAnalogInTriggerSourceSet(hdwf, 11)
# dwf.FDwfAnalogInTriggerSourceSet(hdwf, 2) #one of the analog in channels
  dwf.FDwfAnalogInTriggerTypeSet(hdwf, trigtypeEdge)
# dwf.FDwfAnalogInTriggerChannelSet(hdwf, 1) # 1st channel
  dwf.FDwfAnalogInTriggerLevelSet(hdwf, c_double(0.5)) # 0.5V
# dwf.FDwfAnalogInTriggerHysteresisSet(hdwf, c_double(0.5))
  dwf.FDwfAnalogInTriggerConditionSet(hdwf, trigcondRisingPositive) 
# dwf.FDwfAnalogInTriggerConditionSet(hdwf, trigcondFallingNegative) 
# dwf.FDwfAnalogInTriggerAutoTimeoutSet(hdwf, c_double(0)) #disable auto trigger
  dwf.FDwfAnalogInTriggerHoldOffSet(hdwf, c_double(0))   
# dwf.FDwfAnalogInTriggerChannelInfo(hdwf, c_int(1), c_int(3))
  print("Starting oscilloscope") 
  dwf.FDwfAnalogInConfigure(hdwf, c_bool(False), c_bool(True)) 
  dwf.FDwfAnalogOutConfigure(hdwf, c_int(0), c_bool(True))
  dwf.FDwfDigitalOutConfigure(hdwf, c_int(1))

  time.sleep(3) 

  iSample = 0
 
  while True:
      dwf.FDwfAnalogInStatus(hdwf, c_int(1), byref(sts))
      dwf.FDwfAnalogInStatusRecord(hdwf, byref(cAvailable), byref(cLost), byref(cCorrupted))
      iSample += cLost.value
      iSample %= nSamples
      if cLost.value :
          fLost = 1
      if cCorrupted.value :
          fCorrupted = 1
      iBuffer = 0
#wait at least 2 sec
      while cAvailable.value>0:
          cSamples = cAvailable.value
        # we are using circular sample buffer, make sure to not overflow
          if iSample+cAvailable.value > nSamples:
              cSamples = nSamples-iSample
          dwf.FDwfAnalogInStatusData16(hdwf, c_int(0), byref(rgSamples1, sizeof(c_int16)*iSample), c_int(iBuffer), c_int(cSamples)) # get channel 1 dat
         # dwf.FDwfAnalogInStatusData16(hdwf, c_int(1), byref(rgSamples2, sizeof(c_int16)*iSample), c_int(iBuffer), c_int(cSamples)) # get channel 2 dat
          iBuffer += cSamples
          cAvailable.value -= cSamples
          iSample += cSamples
          iSample %= nSamples

      if sts.value == DwfStateDone.value : # done
          break

  dwf.FDwfAnalogOutReset(hdwf, c_int(0))
  dwf.FDwfDigitalOutReset(hdwf) 

  dwf.FDwfDeviceCloseAll()

# align recorded data
  if iSample != 0:
      rgSamples1 = rgSamples1[iSample:]+rgSamples1[:iSample]

  print("Recording done "+str(iSample))
  if fLost:
      print("Samples were lost! Reduce frequency")
  if fCorrupted:
      print("Samples could be corrupted! Reduce frequency")

  List = [(16.8+j/50.000)*hzAcq.value/500.000]
  for v in rgSamples1:
      List.append(v)
  with open("liqtest2075m.csv", "a") as f_object:
      writer_object = writer(f_object)
      writer_object.writerow(List)
  f_object.close()

AnalogIn_Record_Trigger_int16_si5m.py

[Anthocyanina]

The AD2 has different modes which come with different amounts of memory allocated for each function. I don't know how to do that in the SDK, but on waveforms, to get the 16k points for the scope, you need to pick the second mode as shown in this picture

 About the second question, i don't know, but about the third, the AD2 unfortunately doesn't support alternate trigger, which is what you are describing

Edited April 10, 2023 by Anthocyanina

[attila]

Hi @Zeyu

1. Use FDwfDeviceConfigOpen(c_int(#), c_int(1), byref(hdwf))
See the following:

2. The sleep is only needed after (the first) device connection or offset/range adjustment for these to stabilize.
You can use the following option to keep the device running after sw close, so on the next connection it won't need wait (if you use the same offset/ranges):
dwf.FDwfParamSet(DwfParamOnClose, c_int(0)) # 0 = run, 1 = stop, 2 = shutdown

3. There is one oscilloscope/analog-in instrument and it has one trigger and the channels are sampling in parallel. The trigger option can be changed, like you can change this for consecutive captures.