Using MeasControl.C1StartC2Stop with MultiHarp 150 Doesn't Wait for Trigger

[Lijx130]

I have a MultiHarp150, and I want to use TTL signals on the C1 and C2 control pins to start and stop the measurement.

I’m running the following Python code:

from snAPI.Main import *
import matplotlib
matplotlib.use('TkAgg',force=True)
from matplotlib import pyplot as plt
print("Switched to:",matplotlib.get_backend())

if(__name__ == "__main__"):

    sn = snAPI()
    sn.getDevice()
    sn.initDevice(MeasMode.T2)
    
    # a trigger signal on C1 starts and one on C2 stops the measurement
    sn.device.setMeasControl(MeasControl.C1StartC2Stop.value)
    sn.loadIniConfig("config\MH.ini")
    
    # configure timetrace
    sn.timeTrace.setNumBins(10000)
    sn.timeTrace.setHistorySize(10)
    # prepare measurement for triggered start and stop
    sn.timeTrace.measure(waitFinished=False, savePTU=False) # waitFinished=False means that the measurement will not block the main thread, so we can plot in parallel
    
    plt.figure(f'Figure: {sn.deviceConfig["Model"]}')
    while True: 
        finished = sn.timeTrace.isFinished()
        counts, times = sn.timeTrace.getData() 
        plt.clf()
        plt.plot(times, counts[0], linewidth=2.0, label='sync')
        for c in range(1, 1+sn.deviceConfig["NumChans"]):
            plt.plot(times, counts[c], linewidth=2.0, label=f'chan{c}')

        plt.xlabel('Time [s]')
        plt.ylabel('Counts[Cts/s]')
        plt.legend()
        plt.title(f'TimeTrace Master {sn.deviceConfig["ID"]}') 
        plt.pause(0.1)
        
        print('perform one loop')
        
        if finished:
            print("Measurement finished")
            break
    
    plt.show(block=True)

However, from the terminal output (the printed messages), it seems like the measurement ends immediately without waiting for the trigger signal on C1.

Why is this happening?

Any ideas on how to make the measurement truly wait for a trigger on C1 to start and C2 to stop?

[Angel-O-Lira]

Hi,

Thank you for your inquiry.
Could you share the serial number from the MH150 you are using (it is a number on the back of the equipment usually starts with 010xxxxx)?
Also, which signal are you using for the trigger in your measurement? Rising or Falling edge?
What are the settings you are using such as repetition rate?

In case you want a more personalised support please, go to https://www.picoquant.com/contact/support and contact our support team.

Regards,
Angel Lira.

[Lijx130]

Thank you for your response! I've already resolved the issue. It turned out the problem was caused by using an outdated version of snAPI (v1.0.2). After updating to the latest version (v1.0.7), everything worked perfectly.