Re: LakeShore 335 problem

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Hi Augusto,

• Did you try looking at `dmesg` or `journalctl` at the host to check if there is any information about lost usb devices? 

Thanks for the suggestion.  There are not dmesg errors about lost usb devices, but I do see these errors every time I start the IOC:

[67737.261451] ftdi_sio ttyUSB0: ftdi_set_termios FAILED to set databits/stopbits/parity

[67737.261603] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate

[67737.261747] ftdi_sio ttyUSB0: failed to set flow control: -32

[67737.262037] ftdi_sio ttyUSB0: ftdi_set_termios FAILED to set databits/stopbits/parity

[67737.262167] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate

[67737.262297] ftdi_sio ttyUSB0: failed to set flow control: -32

[67737.262460] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate

[67737.262590] ftdi_sio ttyUSB0: failed to set flow control: -32

[67737.262735] ftdi_sio ttyUSB0: ftdi_set_termios FAILED to set databits/stopbits/parity

[67737.262864] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate

[67737.262993] ftdi_sio ttyUSB0: failed to set flow control: -32

[67737.263146] ftdi_sio ttyUSB0: ftdi_set_termios FAILED to set databits/stopbits/parity

[67737.263275] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate

[67737.263409] ftdi_sio ttyUSB0: failed to set flow control: -32

[67737.265216] ftdi_sio ttyUSB0: failed to set flow control: -32

This is the problem, it is not able to configure the port.

AI told me to try this:

sudo rmmod ftdi_sio

sudo modprobe ftdi_sio

That worked and I can now talk to the device again.  I don't know how it got into a bad state, but I will keep an eye on it.

Thanks,

Mark

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From: Augusto Horita <augusto.horita at gmail.com>
Sent: Tuesday, May 19, 2026 9:18 AM
To: Mark Rivers <rivers at cars.uchicago.edu>
Cc: tech-talk <tech-talk at aps.anl.gov>
Subject: Re: LakeShore 335 problem

Hi Mark,

Did you try looking at `dmesg` or `journalctl` at the host to check if there is any information about lost usb devices? You mentioned that `lsusb` and udev was being activated correctly, but if I understood correctly, that was after reconnection. It would make sense that the device was recognized again after this reconnection, but could be lost before.

Hope this helps.

On Tue, May 19, 2026 at 7:35 AM Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> wrote:

Folks,

I am trying to get a LakeShore 335 temperature controller working with EPICS.  It has both GPIB and USB interfaces.  The USB operates as a serial port at 57600 baud, 7 data bits, odd parity.  Yesterday I connected it to the USB port on Linux, where it was seen as /dev/ttyUSB0.  I set up a udev rule to always connect that vendor, model, and serial number to /dev/lakeshore-335-1 with 666 permissions.  I loaded an IOC with both an asyn record for interactive testing, as well as the LakeShore335.db file which uses StreamDevice here: https://github.com/epics-modules/ip/blob/master/ipApp/Db/LakeShore335.db

Initially it worked fine, I could communicate both with the asynRecord and with the database.  However, after some time it stopped responding to any commands sent to it.  When I disconnect and reconnect the USB cable to the Linux machine it is immediately seen OK, it shows up in lsusb and the udev rule is being activated correctly, so I know the low-level USB interface on the device is working.  I have tried power-cycling several times.

Does anyone know why this might be happening?  There is a Remote/Local switch on the front panel, but it does not communicate in either mode.  Is there some setting that could have been flipped or something?

Thanks,

Mark

--

Augusto Yoshio Horita
Eng. de Controle e Automação - Unicamp
cel.: (19) 98781-1429