[python-vxi11]Abort channel and SQR?

[Blair]

Hi, I'm just learning about both VXI-11 and at the same time discovering python-vxi11. This is fairly general question.

I would like to know whether I can establish an Abort channel and also handle SQRs using python-vxi11? These require separate TCPIP channels and in the second case an RPC server. Has anyone done something like this already (I am using the Keysight E5810 LAN gateway to control some GPIB instruments. I will be running this under linux.)?

[Alex Forencich]

Python-vxi11 will open an abort channel when you call abort.  Initially the abort channel was opened immediately after the link is established, but this was recently changed due to...limitations...of certain device firmware (i.e. noncompliant VXI-11 implementations that do not listen on the advertised abort port and hence cause a timeout when attempting to open the abort channel).  I can certainly add an open_abort_channel method if it would make sense to do so. 

I have a version of python-vxi11 that has some initial support for setting up the interrupt channel...however, I have not had time to flesh it out in part because I'm not sure what the 'best' asynchronous paradigm would be for the server and whatever callback would be used to indicate receipt of the SRQ. 

Alex Forencich

On 11/29/2016 08:47 PM, Blair wrote:

Hi, I'm just learning about both VXI-11 and at the same time discovering python-vxi11. This is fairly general question.

I would like to know whether I can establish an Abort channel and also handle SQRs using python-vxi11? These require separate TCPIP channels and in the second case an RPC server. Has anyone done something like this already (I am using the Keysight E5810 LAN gateway to control some GPIB instruments. I will be running this under linux.)?

--
You received this message because you are subscribed to the Google Groups "python-ivi" group.
To unsubscribe from this group and stop receiving emails from it, send an email to python-ivi+...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Blair]

I see, thank you for the prompt reply.

I think that some ability to respond to SRQs is highly desirable, so I hope that you be able to make a decision soon. I look forward to seeing this in a future release. :-)

[Alex Forencich]

Well, it would be nice to get some insight into how you want to be able to handle SRQs.  I can also update the code I have and place it in a branch so you can play around with it and perhaps flesh it out a bit.  Frankly, I haven't had a need to use SRQs, so I haven't had a strong motivation to get a robust implementation working. 

Alex Forencich

[Blair]

I can only speak about my own requirements.

I use the SRQ facility on GPIB instruments to signal error conditions that arise in the controlled instruments. Such situations are almost never anticipated; they can occur at any stage of a measurement procedure, so I like the asynchronous behaviour of SRQs as a way of signalling.

As I said earlier, I am not really familiar with VXI-11 yet. In my own experience, the SRQ is detected on the GPIB bus controller. It is then necessary to figure out which device raised the request (by polling the instruments on the bus). So the asynchronous call is handled first by a process associated with the controller. I have no idea how this would look in VXI-11 (where there is a channel for each instrument - is there just one SQR channel for callbacks from the instruments). 

Anyway, even this simple functionality would be useful for me: a process that would detect the existence of an SRQ. I would then write something to poll the connected instruments to find out the nature of the problem.

I suppose with VXI-11 it may be possible to have a different callback SRQ channel for every connected instrument, in which case the polling step that I mention above would not be necessary, but I would be quite happy with the simpler model. 

I hope that helps. :-)