When calling a .NET method that has out parameters, you have to supply dummy arguments for the out parameters, can you try something like: result, response, errString = ESP301Device.SR_Get(1, 0.0, '') The values don't seem to matter, but they must be there from what I have seen in my usage. On Fri, Aug 13, 2021 at 9:03 PM LOST _ <lostfreeman@gmail.com> wrote:

Hi Matt,

From the description this looks like a bug in pythonnet. Can you tell which version of pythonnet are you using?

Regards,

Victor

*From: *mysfeir@gmail.com *Sent: *Friday, August 13, 2021 8:59 PM *To: *pythonnet@python.org *Subject: *[Python.NET] "TypeError: No method matches given arguments" Error - please help!

This seems to come up semi-regularly from a web search, but I have been unable to converge on a solution. I am using Python 3.8 and pythonnet to try to control a Newport ESP301 motion controller. The supplied .NET assembly contains this command:

public int SR_Get(int axisNumber, out double limit, out string errstring)

{

errstring = string.Empty;

limit = double.MinValue;

string text = string.Format("{0}{1}", axisNumber.ToString(), "SR");

string text2 = text + "?";

string empty = string.Empty;

StringBuilder sbBuffer = new StringBuilder();

int num = m_COM.Query(text2, ref sbBuffer);

empty = sbBuffer.ToString();

empty = empty.Trim();

errstring = checkReturnCodeAndResponse(text2, num, empty);

if (num == 0 && string.IsNullOrEmpty(errstring))

{

decodeDoubleFromResponse(text, empty, out limit);

}

if (!string.IsNullOrEmpty(errstring))

{

return -1;

}

return 0;

}

I am unable to get this command to run successfully using Pythonnet. Here is my code:

import sys

print("Adding location of Newport.ESP301.CommandInterface.dll to sys.path")

sys.path.append(r'C:\Windows\Microsoft.NET\assembly\GAC_64\Newport.ESP301.CommandInterface\v4.0_2.0.0.3__9f994642f5b48132')

import clr

clr.AddReference("Newport.ESP301.CommandInterface")

from CommandInterfaceESP301 import *

import System

#=====================================================================

# Instrument Initialization

instrument="COM3"

BAUDRATE = 921600

print('Instrument Key=>', instrument)

# create an ESP301 instance

ESP301Device = ESP301()

# Open communication

ret = ESP301Device.OpenInstrument(instrument, BAUDRATE);

if ret == 0:

print("Instrument successfully opened!")

else:

print("Error!")

# Get positive software limit

result, response, errString = ESP301Device.SR_Get(1)

if result == 0:

print('positive software limit=>', response)

else:

print('Error=>', errString)

If I try to execute this code, I get the following error:

====== RESTART: C:\Users\Laser\Documents\Python Programs\esp301_python.py ======

Adding location of Newport.ESP301.CommandInterface.dll to sys.path

Instrument Key=> COM3

Instrument successfully opened!

Traceback (most recent call last):

File "C:\Users\Laser\Documents\Python Programs\esp301_python.py", line 57, in <module>

result, response, errString = ESP301Device.SR_Get(1)

TypeError: No method matches given arguments for SR_Get: (<class 'int'>)

I thought this was originally a problem with int64 vs. int32 but I have tried several methods for converting between these and all give the same error. FWIW, I have no trouble getting this to work in Matlab:

clear

% Add Assembly

NET.addAssembly('C:\Windows\Microsoft.NET\assembly\GAC_64\Newport.ESP301.CommandInterface\v4.0_2.0.0.3__9f994642f5b48132\Newport.ESP301.CommandInterface.dll');

% load modules

import CommandInterfaceESP301.*;

cport = "COM3";

BAUDRATE = 921600;

ESP301Device = ESP301();

% open communication

ret = ESP301Device.OpenInstrument(cport, BAUDRATE);

if ret == 0

disp("Intrument open!")

else

disp("Error!")

end

% Get negative software limit

[result, response, errString] = ESP301Device.SR_Get(1);

I'm completely stumped and frustrated at this point. Any constructive feedback would be very appreciated!

Matt

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I'm not sure, I've had to pass dummy arguments in pretty much every call I have. On Mon, Aug 16, 2021 at 9:44 AM <mysfeir@gmail.com> wrote:

I am using pythonnet version 2.5.2. Slide - your suggestion does fix the problem, thanks. The following code works:

from System import UInt32, Int32 from System import Double result, response, errString = ESP301Device.SR_Get(Int32(1),Double(0.),"")

I think I misread the documentation, which says that calling dummy arguments was necessary with a void method. Is this correct? Otherwise the dummy arguments must always be provided? Thanks again to all for the feedback.

Matt _______________________________________________ PythonNet mailing list -- pythonnet@python.org To unsubscribe send an email to pythonnet-leave@python.org https://mail.python.org/mailman3/lists/pythonnet.python.org/ Member address: slide.o.mix@gmail.com

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