CHIPI-X10 USB to RS232 Converter Cable... LabVIEW compatibility with Keithley instruments?

[RF3000]

I was wondering if anyone has had any experience with the CHIPI-X10 USB-RS232 cable for instruments with LabVIEW? Link here: https://uk.rs-online.com/web/p/serial-converters-extenders/7608711/. I am using LabVIEW 18.

I have been trying to use it to control a Keithley 2401 sourcemeter after having had luck with a USB-GPIB cable and the ready-made VIs that are provided by Keithley, but unfortunately I haven't managed to replicate the results. I installed the drivers from the FTDI website and ensured the serial settings (Baud rate, etc.) match that of the VI, and the converter cable is attached to the PC via a straight-through RS232 cable. The instrument changes to REM (remote mode) when I run any of the standard VIs but the program usually throws up a 1073807339 error. I tried watching with highlight execution and the error is thrown up in the 'Initialise' VI. It also still reliably shows up as a COM port on Device Manager on Windows 10. 

Any advice or help is appreciated. Thanks!

[rolfk]

Most likely a termination character problem. When you use GPIB there is a special hardware line on the bus that is asserted with the last byte of a message by default. This tells the device that the entire command was received and can be now parsed.

RS-232 does not have such a seperate hardware line. Instead it is common to append a specific character at the end such as a carriage return or line feed character. Your instrument driver may not have been written to take such specialities into account.

The underlaying VISA programming interface allows to write instrument drivers that can easily deal with GPIB, serial and VXI-11 instruments with only one version of VIs for all of them but one needs to take a few precautions during the initialisation of the connection to make this work.

So can you upload your driver here?

[RF3000]

Thanks for your reply.

The driver I used can be found here: https://www.ftdichip.com/Drivers/VCP.htm

I downloaded it as a setup executable for Windows on Windows 10.

When testing on NI MAX I tried changing between line feed and carriage return and then queried a *IDN? command, and found that when using carriage return I would get a timeout error, whereas setting the termination to line feed gave a response from the instrument.

[RTSLVU]

I use those CHIPI-X10 USB to RS232 converters all over my lab and they are rock solid with LabVIEW and every other proprietary software I have used. They are not just based on the FTDI chip set but they are in fact manufactured by FTDI.

[NPowl]

It looks as though we found the issue - using a line feed gives a response from the instrument while a carriage return gives a timeout.

If this is a pre-defined driver, you may want to go through and change all the constants for the termination characters to make sure it works with your device in particular.

An "Initialise" function typically asks for a *IDN? command so if we're seeing a failure on initialise then we should be looking at a failure on that read.

Also leaving this here for future people: VISA Error -1073807339 (0xbfff0015) Timeout Expired Before Operation Completed

Cheers,

Nick

[RF3000]

Thanks for all your replies, I managed to find a solution.

The existing Keithley drivers appear to reset the termination character in the VI for serial connections only, there is no problem with GPIB. I ended up writing a new code from scratch which works without problem with the USB/Serial converter.