B4J Question PyBridge question

[walterf25]

Hi all, I just started playing around with PyBridge today, so please excuse my ignorance, I have the following python code which I use at work, it communicates with a Power Supply via USB connection, I am trying to get this to work using B4J and PyBridge, I have python 3.12 installed on my PC.

import pyvisa
import time
import csv
import os

os.add_dll_directory('C:\\Program Files\\Keysight\\IO Libraries Suite\\bin')

# Connect to PLZ205W
rm = pyvisa.ResourceManager()
plz = rm.open_resource("USB0::0x0B3E::0x1042::XF001985::0::INSTR")

# Optional: identify the device
print("Connected to:", plz.query("*IDN?").strip())

# Open a CSV file to store the log
with open("plz205w_log.csv", "w", newline="") as file:
    writer = csv.writer(file)
    writer.writerow(["Timestamp", "Voltage (V)", "Current (A)"])  # Header

    print("Logging started... Press Ctrl+C to stop.")
    try:
        while True:
            voltage = float(plz.query("MEAS:VOLT?"))
            current = float(plz.query("MEAS:CURR?"))
            timestamp = time.time()

            writer.writerow([timestamp, voltage, current])
            print(f"{timestamp:.2f}: {voltage:.3f} V, {current:.3f} A")

            time.sleep(0.5)  # Log every 0.5 seconds
    except KeyboardInterrupt:
        print("Logging stopped by user.")

# Close the VISA connection
plz.close()

I have the following so far inside a function in my B4J project

Private Sub IdentifyKikusui
    Dim ID As PyWrapper = Py.ImportModule("pyvisa")
    Dim OS As PyWrapper = Py.ImportModule("os")
    OS.RunArgs("add_dll_directory", Array($"C:\\Program Files\\Keysight\\IO Libraries Suite\\bin"$), Null)
    Dim rm As PyWrapper = ID.RunArgs("ResourceManager()", Null, Null)) ''Error here
    Dim plz As PyWrapper = rm.RunArgs("open_resource", Array("USB0::0x0B3E::0x1042::XF001985::0::INSTR"), Null)
End Sub

I get an error at the highlighted line, I have tried several ways of running that part of the code but continue getting errors:

(b4xmainpage._identifykikusui) - Python Error (AttributeError) - Method: module.ResourceManager(): module 'pyvisa' has no attribute 'ResourceManager()'

I know I'm doing something wrong but can't figure out what, as I mentioned the python native code works well.

Thanks all for any help provided here.

Walter

 

[Erel]

Start with this:

Dim ID As PyWrapper = Py.ImportModule("pyvisa")
Dim OS As PyWrapper = Py.ImportModule("os")
OS.Run("add_dll_directory").Arg("C:\Program Files\Keysight\IO Libraries Suite\bin")
Dim rm As PyWrapper = pyvisa.Run("ResourceManager")
Dim plz As PyWrapper = rm.Run("open_resource").Arg("USB0::0x0B3E::0x1042::XF001985::0::INSTR")
plz.Print
Do While True
 Wait For (plz.Run("query").Arg("MEAS:VOLT?").Fetch) Complete (Result As PyWrapper)
 Dim voltage As Float = Result.Value
  Wait For (plz.Run("query").Arg("MEAS:CURR?").Fetch) Complete (Result As PyWrapper)
 Dim current As Float = Result.Value
 Log(voltage & ", " & current)
 Sleep(500)
Loop

 

[walterf25]

Start with this:

Dim ID As PyWrapper = Py.ImportModule("pyvisa")
Dim OS As PyWrapper = Py.ImportModule("os")
OS.Run("add_dll_directory").Arg("C:\Program Files\Keysight\IO Libraries Suite\bin")
Dim rm As PyWrapper = pyvisa.Run("ResourceManager(")
Dim plz As PyWrapper = rm.Run("open_resource").Arg("USB0::0x0B3E::0x1042::XF001985::0::INSTR")
plz.Print
Do While True
 Wait For (plz.Run("query").Arg("MEAS:VOLT?").Fetch) Complete (Result As PyWrapper)
 Dim voltage As Float = Result.Value
  Wait For (plz.Run("query").Arg("MEAS:CURR?").Fetch) Complete (Result As PyWrapper)
 Dim current As Float = Result.Value
 Log(voltage & ", " & current)
 Sleep(500)
Loop

Thanks Erel, one quick question, on this line

Dim rm As PyWrapper = pyvisa.Run("ResourceManager(")

Why does it need to be with only the left parentheses and not both left and right parentheses, or is this a typo?

Thanks,
Walter

 

[Erel]

or is this a typo?

this. Fixed.

 

[walterf25]

this. Fixed.

Thanks, will try it tomorrow at work

 

[walterf25]

Start with this:

Dim ID As PyWrapper = Py.ImportModule("pyvisa")
Dim OS As PyWrapper = Py.ImportModule("os")
OS.Run("add_dll_directory").Arg("C:\Program Files\Keysight\IO Libraries Suite\bin")
Dim rm As PyWrapper = pyvisa.Run("ResourceManager")
Dim plz As PyWrapper = rm.Run("open_resource").Arg("USB0::0x0B3E::0x1042::XF001985::0::INSTR")
plz.Print
Do While True
 Wait For (plz.Run("query").Arg("MEAS:VOLT?").Fetch) Complete (Result As PyWrapper)
 Dim voltage As Float = Result.Value
  Wait For (plz.Run("query").Arg("MEAS:CURR?").Fetch) Complete (Result As PyWrapper)
 Dim current As Float = Result.Value
 Log(voltage & ", " & current)
 Sleep(500)
Loop

Hi Erel, I just tried your code and I get the following error

Waiting for debugger to connect...
Program started.
Server is listening on port: 34710
Call B4XPages.GetManager.LogEvents = True to enable logging B4XPages events.
connected
starting PyBridge v0.70
watchdog set to 30 seconds
Connecting to port: 34710
os is: <module 'os' (frozen)>
java.net.SocketException: Connection reset
at java.base/java.net.SocketInputStream.read(SocketInputStream.java:186)
at java.base/java.net.SocketInputStream.read(SocketInputStream.java:140)
at anywheresoftware.b4a.randomaccessfile.AsyncStreams$AIN.readNumberOfBytes(AsyncStreams.java:330)
at anywheresoftware.b4a.randomaccessfile.AsyncStreams$AIN.run(AsyncStreams.java:254)
at java.base/java.lang.Thread.run(Thread.java:834)
disconnected
Process completed. ExitCode: -1073740791
PyBridge disconnected

I had to make one small change as without this change I would get a complete different error:

Dim rm As PyWrapper = pyvisa.Run("ResourceManager").Arg("C:\Program Files\Keysight\IO Libraries Suite\bin\instr32.dll")

I had to add the path argument to point the dll file name, however I get the error above when running the project, also noticed that when trying to print os.print, I see the <module 'os' (frozen)> not sure what this means.

Any ideas what I could try next?

Thanks,
Walter

 

[walterf25]

Ok, made some small changes and seems to work fine now.

    Dim pyvisa As PyWrapper = Py.ImportModule("pyvisa")
    pyvisa.Print
    Dim OS As PyWrapper = Py.ImportModule("os")
    wait for (OS.Run("add_dll_directory").Arg("C:\\Program Files\\Keysight\\IO Libraries Suite\\bin").Fetch)Complete(res As PyWrapper)
    res.Print
    
    Dim rm As PyWrapper = pyvisa.Run("ResourceManager")'''.Arg("C:\Program Files\Keysight\IO Libraries Suite\bin\instr32.dll")
    rm.Print
    wait for (rm.run("list_resources").Fetch) complete(l As PyWrapper)
    l.ToList.Print
    Dim plz As PyWrapper = rm.Run("open_resource").Arg("USB0::0x0B3E::0x1042::XF001985::0::INSTR")
    wait for (plz.Run("query").Arg("*IDN?").Fetch) complete(result As PyWrapper)
    result.Print
    
    wait for (plz.Run("query").Arg("DATA:BSIZ?").Fetch) Complete(datsize As PyWrapper)
    datsize.Print
    
    wait for (plz.Run("query").Arg("DATA:FORM?").Fetch) Complete(format As PyWrapper)
    format.Print
    
    plz.Run("write").Arg("DATA:INT:GATE NONE")
    
    wait for (plz.Run("query").Arg("DATA:INT:GATE?").Fetch) complete(dataint As PyWrapper)
    dataint.Print
    
    plz.Run("write").Arg("DATA:INT:STAR")
    
    Do While True
        Wait For (plz.Run("query").Arg("MEAS:VOLT?").Fetch) Complete (result As PyWrapper)
        Dim voltage As Float = result.Value
        wait for (plz.Run("query").Arg("DATA:POIN?").Fetch) complete (datapoint As PyWrapper)
        datapoint.Print
        Wait For (plz.Run("query").Arg("MEAS:CURR?").Fetch) Complete (result As PyWrapper)
        Dim current As Float = result.Value
        Log(voltage & ", " & current)
        lblVoltage.Text = NumberFormat(voltage, 0, 4)
        lblCurrent.Text = NumberFormat(current, 0, 4)
        Sleep(500)
    Loop

Very cool stuff @Erel really cool stuff!

How can I retrieve the plz pywrapper object from anywhere in my code, let's say I want to Stop the Data Integration from the B4XPage_Disappear sub
Like this

plz.Run("write").Arg("DATA:INT:STOP")

Rather than creating a global variable for plz pywrapper, is there a way to access this from anywhere else in the code?

Thanks,
Walter

 

[Erel]

Why not create a global variable for this? Exactly like you would have done with "pure B4X" code.

And make sure to exit the endless loop. Change Do While True with Do While Working where Working is a global variable.