Configuring U3 to count pulses

Hi Guys, 

I am new to this and hope I can get a pointer in the right direction. I am doing an experiment where I need to stream 4 analogue inputs to measure voltages and one digital input to count pulses from a radiation detector. 

The pulses from the radiation detector are 3.3V square waves of around 50 microseconds, and I need to get the counts per second.

I have the 4 analogue inputs working, but not sure how to configure the last input for the detector.

Any assistance would be appreciated.

Steven

https://www.gammaspectacular.com

import sys
import traceback
from datetime import datetime
import time
import u3

def labjack(num_samples):
    MAX_REQUESTS = 100    # Number of requests per second
    SCAN_FREQUENCY = 20000   # Hz

    d = None
    d = u3.U3()
    d.configU3() #  Check if U3 is HV
    d.getCalibrationData()
    d.configIO(FIOAnalog=4) # Set the FIO0 to FIO3 to Analog (d3 = b00000011)
    d.streamConfig(
        NumChannels=4, # Number of channels to stream
        PChannels=[0, 1, 2, 3], # Numbers 0-7 for positive channel inputs
        NChannels=[31, 31, 31, 31], # Numbers 0-7 for negative voltage inputs or 32 for single ended
        Resolution=3, 
        ScanFrequency=SCAN_FREQUENCY)

    try:
        d.streamStart()
        missed = 0
        dataCount = 0
        packetCount = 0
        readings = {"AIN0":[],"AIN1":[],"AIN2":[],"AIN3":[]}

        for r in d.streamData():
            if len(readings["AIN0"]) >= num_samples:
                d.streamStop()
                d.close()
                break

            if r is not None:
                if r["errors"] != 0:
                    print("Errors counted: %s ; %s" % (r["errors"], datetime.now()))

                if r["numPackets"] != d.packetsPerRequest:
                    print("----- UNDERFLOW : %s ; %s" %
                          (r["numPackets"], datetime.now()))

                if r["missed"] != 0:
                    missed += r['missed']
                    print("+++ Missed %s" % r["missed"])
                
                for k in readings.keys():
                    readings[k] += r[k]
                
                dataCount += 1
                packetCount += r['numPackets']

            else:
                print("No data ; %s" % datetime.now())
    except:
        d.streamStop()
        print("Stream stopped.\n")
        d.close()

    now = int(datetime.now().strftime('%s%f'))
    avgs = {'time':now}

    for k in readings.keys():
        avgs[k] = sum(readings[k])/len(readings[k])    
        d.close()

    return avgs

while True:
    avgs = labjack(100)
    print(avgs)