CODEWITHSUNDEEP
pythonvisapyvisa
Paul Chernoch
Paul Chernoch

Reputation: 5553

What connection string do I use for pyvisa when my TCP device is connected via a USB to Ethernet Adapter?

I am attempting to communicate with a BraggMETER Interrogator that supports SCPI.

OS: Windows 10

Connection hardware: j5create JUH470 USB 3.0 Multi-Adapter Gigabit Ethernet / 3-Port USB 3.0 HUB

Part of my confusion: Should I access as a USB device or as a TCPIP device?

When I connect via Telnet, all goes well. The IP Address and Port are 10.0.0.10 and 3500.

> telnet
> open 10.0.0.10 3500
:IDEN?
:ACK:HBM FiberSensing:FS22SI v3.0:08:046 840 200 898:20190116
:STAT?
:ACK:1

In Python, I am usig the pyvisa library.

import easy_scpi as scpi
import pyvisa

DeviceAddress = '10.0.0.10'
DevicePort = '3500'
VISADevice = f'TCPIP0::{DeviceAddress}::{DevicePort}::SOCKET'
# Doesn't work either --> VISADevice = 'ASRL10::INSTR'

rm = pyvisa.ResourceManager()
print(rm.list_resources())

inst = rm.open_resource(VISADevice)
print(inst.query("*IDEN?"))
inst.close()

The error is always on rm.open_resource. I have tried numerous connection strings. They give different errors. Here are three of them:

pyvisa.errors.VisaIOError: VI_ERROR_INTF_NUM_NCONFIG (-1073807195): The interface type is valid but the specified interface number is not configured.

pyvisa.errors.VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.

pyvisa.errors.VisaIOError: VI_ERROR_RSRC_NFOUND (-1073807343): Insufficient location information or the requested device or resource is not present in the system.

Update 1

I downloaded National Instruments NI-Max and used their NI I/O trace. This connection string "works":

TCPIP::10.0.0.10::3500::SOCKET

However, I still get the timeout error. Tried ensuring that the newline termination character is sent and upped the timeout to 5 seconds (which did take effect, as it delayed the logging of the timeout error). No dice. Still gives a timeout error.

Update 2

While not the same setup, someone else reports a problem who is using an NI GPIB-to-USB card (GPIB-USB-HS). The common thread is a USB adapter...

https://community.keysight.com/thread/37567

Upvotes: 0

Views: 3522

Answers (2)

Paul Chernoch
Paul Chernoch

Reputation: 5553

The problem was that the device exects CRLF (carriage return plus linefeed) as an SCPI command terminator. I was only sending one of those two characters, "\n".

Python I/O does not adapt to the OS like some languages I have used, which will interpret "\n" as "\r\n" in some situations.

Likewise, NI-Max only sent the "\n" and omitted the "\r".

Upvotes: 1

Zircatron
Zircatron

Reputation: 146

I'm not able to comment so I'm commenting here

Have you tried using a normal socket?

import socket

DeviceAddress = '10.0.0.10'
DevicePort = '3500'
BUFSIZ = 1024
ADDR = (DeviceAddress, DevicePort)
cmd = "IDN?" # or "*IDEN?" as you've put?

braggMeterSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
braggMeterSocket.connect(self.ADDR)
braggMeterSocket.send(cmd + "\n") #maybe with new line depending on what the device terminator is.
mesg = braggMeterSocket.recv(BUFSIZ)
mesg = mesg.strip() # Remove \n at end of mesg
print(mesg)

Upvotes: 1

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