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Post by vasilis on Jan 4, 2024 1:52:01 GMT -5
Hello all, I have been interfacing a temperature controller model 335 and interfacing on a windows 7 computer via GPIB. I am changing the computer (Windows 10) and I decided to try out the USB connection. I was able to download the drivers via Windows update, and I checked that they are the same versions are the ones manually downloaded from the lakeshore website. The USB cable is short (50 cm, did try different cables) and properly connected. I am trying to use python to interface with the device. - I tried using pyvisa, where I get the resourceManager, I list the devices and then I attempt to open the resource (e.g. port/name 'ASRL8::INSTR'). I am able to open the resource. However, Whatever I write, the reading times out. I followed all the troubleshooting instructions per the manual. Whichever termination characters with or without commands I have tried (even the basic '*IDN?') the read always times out. I have tried to increase the time out time, and also give plenty of time between write and read (I also tried query).
- I tried using the python software lakeshore provides. I attempt to open 'COM8' with baud rate of 9600. The first attempt times out (I set the timeout to 10 s), the second attempt is access-denied (PermissionError(13, 'Acces is denied.', None, 5), and the third attempt goes back to timing out, etc.
- I tried the same thing on another computer. I have tried with different USB cables of different sizes. The above behavior was always the same.
- On the other computer (also windows 10), I tried using the NIMAX application to view and access the device. The result was the same as trial #1 (with python pyvisa).
- I checked the GPIB connection on the second computer (as in #4), and the device responds as expected.
Summary
USB connection fails to establish communication between the computer and the device while GPIB interfacing works as expected. What are some next steps I can take to troubleshoot this? |
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Post by vasilis on Jan 4, 2024 14:06:32 GMT -5
Quick update! I was able to get the device to connect with the lakeshore API in python. I had to use a baud rate of 57600, which was listed in the device manual (silly me...). However I am still having trouble. I can neither write, query or read from the lakeshore API. I tried instead to use pyvisa and change the baud rate. I am able to write, and I can see that there is something in the buffer via the resource.bytes_in_buffer property which is 35 if I query the IDN. However, when I try a simple read, I get a timeout error. if I try a read_bytes(35), I get the following bytes: b'L\xd3CI,\xcdO\xc4EL\xb3\xb3\xb5,\xb3\xb3\xb5\xc1\xb04\xd0/#######,1\xae\xb0\r\x8a'. I have tried multiple different codecs, and none of them is able to decode this byte string. Hope this is insightful to what the problem is.
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Post by Lake Shore Jeff M on Jan 4, 2024 14:28:17 GMT -5
The first thing I want to do is verify you have installed the Lake Shore USB Driver for Windows 10 or later and that you see the Model 335 listed with a COM Port assigned in the Device Manager Ports (COM & LPT) tree when the USB is connected. If you see a COM Port assigned, please install the free Instrument Communications Utility found in the software section on the web site and see if you can connect and send the *IDN? query command and receive the correct response. This will confirm that the physical connection is working and then we can look at the Python Code.
If this works and you still have issues with the python script, please send the script file to support@lakeshore.com so we can have our engineering team review your code and advise what would be needed to resolve the issue.
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Post by vasilis on Jan 9, 2024 13:18:01 GMT -5
Hello, Thank you for your response! The drivers were already installed, and I could see the device on NI MAX with a specific COM port assigned (COM5 for this computer). I was not aware of the "Instrument Communication" software. It was quite easy to setup. I selected the right COM port and queried "*IDN?" with the default settings. I got this string: "LÓCI,ÍOÄEL³³µ,³³µÁ°4Ð/#######,1®°". However when I changed the setting from "XIP / Model 240" to "Legacy Instruments" and query "*IDN?" I get "LSCI,MODEL335,335A04P/#######,1.0"!! I was then able to query other values and the response was reasonable. Thank you for pointing me to this tool!
After that, I found what the problem was when I was configuring the pyvisa code. By clicking "Help" on the top right of the "Instrument Communication" Utility window, I was able to find what the difference is between XIP and Legacy instruments. Apparently, the default pyvisa settings (matching the XIP settings) are data_bits=8 and parity=None. However, for the legacy instruments data_bits=7 and parity=Odd (putting 1 for pyvisa would do the trick). Once you change these settings (as well as the baud rate to 57600). So for anyone trying to do something similar, here is the successful code:
import pyvisa
rm = pyvisa.ResourceManager()
# rm.list_resources() -> to see which resources are connected.
# Assume resource is on 'COM1' (or 'ASRL1::INSTR').
model_335 = rm.open_resource('ASRL1::INSTR', baud_rate=57600, data_bits=7, parity=1)
Retrospectively, I should have paid a lot more attention to page 100, chapter 6.3.2 "USB Interface - Hardware Support" of the manual. Thank you for help, and providing very detailed documentation (even though I was too blind to find what I was looking for).
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Post by Lake Shore Jeff M on Jan 9, 2024 14:12:46 GMT -5
I am glad to hear you are up and running as I should have mentioned to use the Legacy setting.
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Post by trabrucks on Mar 28, 2024 3:00:57 GMT -5
Hello all, I have also an issue with USB connection to PC. I can see LS335 on COM3 from device monitor, and also in NI MAX as ASLR 3 (COM3). Thanks to Vasilis, I read page 100 of the manual , and set carefully the parameters on NI MAX. I also installed the usb driver, and I was also able to communicate with LS335 using the free Instrument Communications Utility using query IDN?
But the problem is that I cannot use NI MAX to send the command *IDN? to COM3. VISA is installed. I use Windows 11 64 bits on Dell. I don't have a souvenir to have installed JAVA. It was mentioned in another post.
My goal is to use USB to PC, and control LS335 with Labview 2024 x64. I have to say that I have 3 lakeshore 335 in the lab. One is used manually, no PC. The other one is connected to GPIB interface and it works like a charm with NI MAX and Labview 2024. But I never succeeded to use the USB cable to control the instrument. So, I would like to improve my skills, cause there is something that I cannot really catch from this particular instrument. Note that in my setup, I use many instruments, with USB and GPIB either, everything works. Could you please guide again to a successful control of LS 335 via USB and labview ?
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Post by Lake Shore Jeff M on Apr 3, 2024 12:58:31 GMT -5
The Model 335 requires a Line Feed Character as the termination of the input string. You have to Tell NIMAX to use this character. In the VISA Test Panel Click on the I/O Settings Tab:
Check the Enable Termination Character box
Set End Mode Reads as None
Set End Mode for Writes as Termchar
Select Termination Character Line Feed \n
then Apply Changes
Click the View Attributes and Verify that the Enable Termination Character value is VI_TRUE
Select the Input/Output Icon and click the Query button.
If everything is correct you should see the Model 335 Identification information.
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