[Python] pyvisa script only works when stepping through code

I have written a small python script to enable the output of a HAMEG HMG4040 triple power-supply. I am using pyvisa 1.14.1 along with NI-VISA 20.0

import pyvisa
import time

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

# List all connected VISA devices
def list_devices():
devices = rm.list_resources()
if devices:
print("Available VISA devices:")
for idx, device in enumerate(devices):
print(f"{idx + 1}: {device}")
else:
print("No VISA devices found.")
return devices

# Function to query the device
def query_device(resource_name, command):
try:
# Open the device resource
with rm.open_resource(resource_name) as instrument:
instrument.timeout = 5000 # Set timeout to 1000 ms (1 seconds)
# Write the query command to the device
instrument.write(command)
# Read the response from the device
response = instrument.read()
return response
except Exception as e:
print(f"Error querying device: {e}")
return None

# Function to query the device
def send_cmd_device(resource_name, command):
try:
# Open the device resource
with rm.open_resource(resource_name) as instrument:
instrument.timeout = 5000 # Set timeout to 1000 ms (1 seconds)
# Write the query command to the device
instrument.write(command)
return 1
except Exception as e:
print(f"Error querying device: {e}")
return None

# Main function
if __name__ == "__main__":
# List available devices
devices = list_devices()

if devices:
# Choose the device you want to query
resource_name = devices[0] # Use the first detected device for this example

# Command to send to the device (replace with actual command)
command = "*IDN?"

# Query the device and get the response
response = query_device(resource_name, command)

if response:
print(f"Response from HMG4040: {response}")
else:
print("No response from the device.")

state = input("specify PSUP state: [ON/OFF]\n")

#select and activate output 1,2 and 4

with rm.open_resource(resource_name) as instrument:
instrument.timeout = 1000 # Set timeout to 1000 ms (1 seconds)
instrument.write("INST OUT1")
instrument.write("OUTP:SEL " + state)
instrument.write("INST OUT3")
instrument.write("OUTP:SEL " + state)
instrument.write("INST OUT4")
instrument.write("OUTP:SEL " + state)
instrument.write("OUTP:GEN " + state)

send_cmd_device(resource_name, "INST OUT1")
send_cmd_device(resource_name, "OUTP:SEL " + state)
send_cmd_device(resource_name, "INST OUT3")
send_cmd_device(resource_name, "OUTP:SEL " + state)
send_cmd_device(resource_name, "INST OUT4")
send_cmd_device(resource_name, "OUTP:SEL " + state)
send_cmd_device(resource_name, "OUTP:GEN " + state)

else:
print("No devices to query.")


If I comment out the "send_cmd_device()" lines the script is working fine either in debug mode or normal python execution.

However, if I comment out this part:

with rm.open_resource(resource_name) as instrument:
instrument.timeout = 1000 # Set timeout to 1000 ms (1 seconds)
instrument.write("INST OUT1")
instrument.write("OUTP:SEL " + state)
instrument.write("INST OUT3")
instrument.write("OUTP:SEL " + state)
instrument.write("INST OUT4")
instrument.write("OUTP:SEL " + state)
instrument.write("OUTP:GEN " + state)


The script only works if I place a breakpoint and step, in debug mode, through each line including the "send_cmd_device()" lines.

Could someone explain why the script doesn't work in normal full speed exection when using the method call? I have tried adding delays everywhere but that didn't help.

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