Setting up a GPIB communication with Keithley 220 and HP 34401A

[appleSwell]

Hi everyone,

I am using GPIB-USB-HS to connect both Keithley 220 Current Source and HP 34401A Multimeter and send commands via LabVIEW. I am using an existing old LabVIEW code, but I keep running into the problem (Error 7, file not found) when I send the command through GPIB Write Function, "INP:IMP:AUTO ON" (which sets the multimeter in high impedance).

And so, I am climbing down to the low level subVIs. However, it looks like I can't even run this simple voltage reader VI. There is simply no output string when I run the program, and so I assume I am not communicating with 34401A

In order to figure out whether the devices are connected to the computer via usb cable, I ran NI MAX program, and I GPIB-USB-HS "GPIB1" is visible under Devices and Interfaces.

What am I missing? One of my confusions is how to set GPIB address of two devices. Do I set them with the same address? I am confused then how, when sending a GPIB Write command, we can select one of the two devices (220 and 34401A). 

[Tepig]

Hare you tried "Scan Instrument" in NI MAX?

GPIB Instrument Control Tutorial

After you finish the operation, you can see GPIB devices which are connected.

[appleSwell]

Thank you. Scan for Instruments indeed show the two devices--Keithley 220 and HP34401A with GPIB address. This answers the question I had before.

I can now communicate with Keithley 220, but HP34401A is still non-responsive to LabVIEW commands. 34401A is in continuous measurement mode, as it shows correct voltage value on the front screen, as I control the current of 220 by LabVIEW.

Considering the computer recognizes 34401A, at least according to NI MAX, I believe there is some kind of a "button" I need to press on 34401A when I re-connect the GPIB cable. Someone else has been using this exact system on the same computer a week ago, and it was working just fine. I just disconnected GPIB cable and re-connected it, and it suddenly stops working.

[Tepig · Accepted solution]

it seems that you should change the instrument mode to "remote".

See the manual.

[Minions · Accepted solution]

Other than placing the HP 34401A into remote, you will need to manually set the language to SCPI.