How to Program Test Tools with Python - Workbench Wednesdays 66

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>>> import serial; ser = serial.Serial('COM3', 115200, timeout=5); ser.write(b'*IDN?\n\r'); ser.close()
7
>>> import serial; ser = serial.Serial('COM3', 115200, timeout=5); ser.write(b'*IDN?\n'); ser.close()
6
>>> import serial; ser = serial.Serial('COM3', 115200, timeout=5); ser.write(b'*IDN?'); ser.close()
5
>>> import serial; ser = serial.Serial('COM3', 115200, timeout=5); ser.write(b'RST'); ser.close()
3
>>>

Try to add a newline.

SCPI Command Terminators:

A command string sent to the instrument must terminate with a <new line> (<NL>) character. 

Unfortunately not, 

import serial; ser = serial.Serial('COM3', 115200, timeout=5); ser.write(b'*IDN?')

Output: 

4 or 5

Does it work when you connect through a serial terminal and type commands?

import serial
import time

# Define serial port settings
port = 'COM3'
baud_rate = 115200 #9600
timeout = 1

# Open serial port
ser = serial.Serial(port, baud_rate, timeout=timeout)

try:
    # Send SCPI command to query instrument identification
    command = "*IDN?\n" #\n\r
    ser.write(command.encode())  # Send the command as bytes
    time.sleep(0.3)

    # Read response from the DMM
    response = ser.read_all().decode()
    print("Instrument Identification:", response.strip())
except serial.SerialException as e:
    print("Serial communication error:", e)
finally:
    # Close serial port
    ser.close()

Output: 

Instrument Identification: 

Process finished with exit code 0

A serial connection is established successfully, but the digital multimeter (DMM) does not respond to the commands sent to it

I would try using a serial terminal to connect to it first. That way you might be able to figure out what it is doing.

Thank you for sharing this informative video! I found it really helpful in understanding how to program and test tools with Python.

I have a question regarding the VICTOR 8246A DMM. Despite my efforts, I couldn't locate any proper documentation for this model, especially concerning remote connectivity. I'm attempting to establish a remote connection with the instrument but haven't had much luck. Do you have any advice or resources you could recommend?

Thanks in advance for any assistance you can provide!

Here is the Hello World code: 

import pyvisa
from time import sleep  # for delays

# Initialize the PyVISA resource manager
ResourceManager = pyvisa.ResourceManager()

# List all connected resources
print("Resources detected\n{}\n".format(ResourceManager.list_resources()))
#Resources detected ('ASRL4::INSTR', 'USB0::###############', 'ASRL3::INSTR')


# Open a connection to the DMM (Digital Multimeter) device
DMM = ResourceManager.open_resource('ASRL3::INSTR')

# Set the baud rate for the serial interface
DMM.baud_rate = 115200
DMM.query_delay = 0.3
DMM.write_termination = '\n'
DMM.read_termination = '\n'

# Print information about the connected device
print(DMM) # SerialInstrument at ASRL3::INSTR

# Send command to the DMM to query its identification
print(DMM.query("*IDN?"))

# Close the connection to the DMM
DMM.close()

Here is the error that I got: 

, line 251, in handle_return_value raise errors.VisaIOError(rv)
pyvisa.errors.VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.

you are the best 

I am glad it is working! I sincerely apologize because I forgot about the udev rule.

I set it up so long ago that I forgot the step was necessary! (And it should have been in the video!)

Like I said in the video, getting to "*IDN?" is probably the hardest step of all!

Dear Mr. James, I would like to express my sincere gratitude for your support. Thanks to your help, it is now working. I greatly appreciate your patience and expertise.