Keithley 2601A and Prologix GPIB 6.0 communication

[Jbox]

I am using a Keithley 2601A SourceMeter with a Prologix GPIB 6.0 to USB controller. This GPIB controller (installed according to the directions, before you ask) makes the instrument appear on the Device Manager on an emulated serial port (COM3). However, every time I try to run even a simple program (see attached quick test.vi), the instrument does not read any data nor does it return any to the computer. Instead, the instrument's display reads "ERROR CODE: -420 Query Unterminated" even though I explicity concatenate the correct terminator (a line feed character). I have even tested the program with no line feed character, since I believe the Prologix controller is configured to submit one on its own. Nonetheless, the same response is given.

I have also been using an RS-232 serial connection (COM1), and that allows the instrument to function according to the intent of my program. However, I would much prefer to use GPIB because I need to use the RS-232 connection for another instrument and I have a GPIB splitter for yet a third instrument.

Any help would be greatly appreciated.

[Dennis_Knutson]

If that VI works when you select Com1, then there is something wrong with your use of the prologix converter and I think you should be contacting them.

You should also do the debug of the communication through the Prologix with Hyperterminal.

Imho, the prologix is a tool for hobbyists. You cannot use any of the existing drivers so the money you save on the hardware is spent on rewriting existing code.

p.s. What is this GPIB splitter?

Message Edited by Dennis Knutson on 07-01-2009 01:06 PM

[cymrieg · Accepted solution]

This is right out of the Prologix manual:

NOTE:

Some instruments generate “Query Unterminated” or “-420” error if they are addressed

to talk after sending a command that does not generate a response (often called nonquery

commands). In effect the instrument is saying, I have been asked to talk but I have

nothing to say. The error is often benign and may be ignored. Otherwise, turn off readafter-

write feature before issuing non-query commands. Later turn on the feature after

issuing query commands to read response. For example:

++auto 0 — Turn off read-after-write and address instrument to listen

SET VOLT 1.0 — Non-query command

*idn? — Query command

++auto 1 — Turn on read-after-write and address instrument to talk

"HP54201A" — Response from instrument

Or, use the ++read command to read the instrument response. For example:

++auto 0 — Turn off read-after-write and address instrument to listen

SET VOLT 1.0 — Non-query command

*idn? — Query command

++read eoi — Read until EOI asserted by instrument

"HP54201A" — Response from instrumen

[Jbox]

I had noticed that part of the manual (having combed over it), but I didn't really understand how to apply it correctly. After a lot of different attempts, I have it working properly. Thank you.

[Mutha]

Hi 

I have the similar issue.Am able to do the basic_read_write with the Prologix GPIB Controller.However Am unable to get the 'Handshaking' possible as protocol for GPIB-USB and instrument drivers of Model 330 Autotuning Temperature Controller are different.As the instrument drivers are programmed to read from a GPIB device.

Could you please tell me your method that worked ?

Also would you recommend me to buy another controller instead ??

Please suggest.

Thank you

Muthahera

[sgnape_sot_la_nape]

I've a similar problem.

I'm using a Prologix to communicate to an AGILENT 34401a. I want to use "Instrument driver" VIs provided by NI,

but Agilent34401.libvi:Error Query.vi  (called by other modules of Instrument driver Agilent library) always exits with an error by this reason: -420

Prologix suggest to set ++auto 0, but in this way the "Instrument driver" LABView interface doesn't work at all ! so I've changed  

Agilent34401.libvi:Error Query.vi to skip error -420 

Perhaps the vi is done to connect the instruments with a NI gpib connector. It's not nice to update VI's downloaded from the NI site, but I cannot otherwise

[Dennis_Knutson]

You either update the driver, write your own, or use a real GPIB controller. The driver works perfectly fine with a controller from NI, Agilent, and Keithley (among others). Getting help from prologix is your best option.