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
