Measurement of delay between two signals using MSO4104 with PyVisa

Question

I need to automate the measurement of delay between two signals using the oscilloscope. I am using MSO4104 from Tektronix. I programmed the oscilloscope for delay measurement, but I am not getting the output.

The measurement conditions are given below:

Signal 1

High-90%,Mid,20% Low 10% and EDGE-Falling

Signal-2 Low 10% ,Mid 20%, High 90 EDGE Raising

Please see my code below. After executing this code output is not coming.

Can you please tell me where I went wrong?

import pyvisa
from time import *
rm = pyvisa.ResourceManager()
rm.list_resources()
#print(rm.list_resources())
scope = rm.open_resource('USB0::0x0699::0x0401::C002760::0::INSTR')
IDN = scope.query('*IDN?')
print ('Successfully connected to: ', IDN)
scope.write("*RST")
scope.write('SELECT:CH1 ON')
scope.write('SELECT:CH2 ON')
scope.write("AUTOset EXECute")
sleep(5)
scope.write("MEASUrement:REFLevel:METHod PERCent")
scope.write("MEASUREMENT:IMMED:DELAY:DIRECTION FORWARDS")
#For Channel_1
scope.write("MEASUrement:IMMed:SOURCE CH1")
scope.write("MEASUrement:IMMed:DELay:EDGE1 FALL")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:HIGH 90")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:MID 20")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:LOW 10")
#For Channel_2
scope.write("MEASUrement:IMMed:SOURCE CH2")
scope.write("MEASUrement:IMMed:DELay:EDGE2 RISE")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:LOW 3")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:MID 20")
scope.write("MEASUREMENT:REFLEVEL:PERCENT:HIGH 80")
sleep(10)
scope.write("MEASure:DELay CH1,CH2")
sleep(10)
Delay_1_2 = scope.query('MEASure:DELay? CHANNEL1,CHANNEL2')
print('Delay is:',Delay_1_2)
scope.close()
rm.close()

Answer 1

Below is a script to measure delay in Ch1 - Ch2 raising edges with MDO4042 Tek scope.
I had to improvise to make delays between Ch1 and 2, so please tune the script to your needs.

#Script to measure delay with MDO4024C Mixed Domain Oscilloscope
import time
import pyvisa as visa
rm = visa.ResourceManager()
print('Available devices: ')
print(rm.list_resources())  #to check instruments connected
try:
    scope = rm.open_resource('USB0::0x0699::0x0456::C000197::INSTR', send_end = True)  #adding scope
    print('Device open: ', scope)
except:
    print('Opening device problem')

IDN = scope.query('*IDN?')
print ('Successfully connected to: ', IDN)

#---SCOPE SETUP---
scope.write("*RST")
scope.write('SELECT:CH1 ON')
print('Select Ch1: OK')

scope.write('SELECT:CH2 ON')
print('Select Ch2: OK')

scope.write('AUTOset EXECute')
print('Autoset: OK')

scope.write('HORizontal:SCAle 4E-3') #set horizontal scale to 4ms
print('Horizontal scale set to 4ms')

scope.write('TRIGger:A SETLevel') #set trigger level to 50% of range
print('Trigger to 50% of the range')

scope.write('MEASUrement:IMMed:DELay:DIRection FORWARDS')
print('Measurement type sent: OK')

scope.write('MEASure:DELay CH1,CH2')
print('Command sent: MEASure:DELay CH1,CH2')


scope.write('MEASurement:IMMed:TYPe DELay')
time.sleep(1)

#--checks to confirm---
#scope.write('MEASurement:IMMed:TYPe?')
#time.sleep(0.5)
#print(scope.read())
#-------
#time.sleep(2)
#scope.write('MEASurement:IMMed:DELay?')
#time.sleep(0.5)
#print(scope.read())
#-----------
#time.sleep(2)
#scope.write('MEASurement:IMMed:UNIts?')
#time.sleep(0.5)
#print(scope.read())
#-------

while True:
    scope.write('MEASurement:IMMed:VALue?')
    time.sleep(0.5)
    print(scope.read())

Commented part was used to confirm type of measurement, settings and units.
Below is a picture of returned values:

Two first received values shows some problems (scope manual say this specific value is normally associated with error), anyway later values are correct.