empty read buffer

[ulf.kulinna]

Hi there!

I´m currently trying to visualize one of our Keithley DMMs via VISA (USB and/or ethernet). Unfortunately I´m struggling with several issues:

1) I have implemented a query for the existing buffers in the device. But as the device returns nothing on a request for a list of buffers, my application fails as the read buffer´s empty. Is there a way to get information about the size of the read-buffer or any other way to prevent the error message?

2) is it possible to write something into the VISA-buffer (to prevent the problem in 1))?

3) How can I disable the interpretation of the termination char for VISA, not only for serial, but also for TCP/IP-devices?

Thanks in advance!!

[Dennis_Knutson]

What's the model number of the DMM? What language are you using and have you done a search for an existing driver?

The only thing that can place data in the read buffer is the instrument and if there is nothing in the buffer, you probably have not sent the correct command to the instrument requesting a read.

The termination character enable/disable is set with a VISA property node (Message Based Settings:Termination Character Enable). Look inside the VISA Configure Serial Port.

[ulf.kulinna]

First of all thanks for your help!

It´s a Keithley 3706 and there´s drivers available from Keithley. But unfortunately they do not include all functionality I need to have. I use the TestScriptProcessor inside the DMM which is capable of handling instructions like loops in a formatless way. Example: "for name in dmm.buffer.catalog() do print(name) end" returns a list of all buffers. But in case there´s no buffers existing, there is no answer...If there a some, they are returned, divided by "\n" (that´s the reason behind the other question).

Is there any chance to get the size of the read-buffer?

Configuring the serial port seems not to work as I get an error message in case the DMM is connected via TCP/IP.