read status of SCXI switch during scan mode

[kudigu]

I am using SCXI-1193 switch with LabView 8.0

To change the connections I am using an external trigger and a scan list.

I am wondering if there is a way to check the actual connection status of the switch while running in scan mode.

I would be happy also for alternative solutions.

Thanks,

Guido

[chericks1]

Hi Guido,

The SCXI-1193's connection status can not be viewed with the Switch Soft Front Panel or queried by API calls when the switch module is running in scan mode.  However, the switch can output a scan advanced trigger.  You can count how many triggers have occurred and compare this value with the scan list entries to find out where exactly the switch module is at in the scan list.

Hope this helps!

Chad Erickson

Switch Product Support Engineer

NI - USA

[kudigu]

Hi Chad,

that works fine. Thank you for your fast help.

Although a Property Node or a seperate VI to check the actual state would be a useful tool in the future.

Guido

[chericks1]

Hi Guido,

Thank you for the suggestion!  I discussed this with several members of the Switches Software R&D team and I have some questions for you.

1. How would you use this state information in your application?  For example:

a) Is it to troubleshoot? Do you want the switch state to verify the switch module is operating as expected?  

b) Do you want to present this information visually on the front panel?  Are you envisioning an update tool similar to the Switch Soft Front Panel? 

c) Do you want to use the switch state as a selector to determine which cases execute in your code?

2. Would a property node that provides an updated number of received switch input triggers be sufficient information? 

Note: This technique would be less accurate compared to counting switch scan advanced triggers, as the software polling is not likely to keep up with the scan list. 

Thanks again!

Chad Erickson

Switch Product Support Engineer

NI - USA

[kudigu]

Hi Chad,

Thanks for your effort.

1.a) Right. I would use the information for verification. A power measurement is connected to the SCXI 1193 and this is switching between different channels. For adjustment and calibration I must be sure that I am looking on the right channel.

b) Yes, there will be some boolean indicators or a string field which shows the actual channel. It will be for indication only not for control like the SSFP.

c) No, I am basically use the switch for measurement.

2. Counting switch advanced triggers is a quite easy and good solution. So I think a property node with the count of triggers would be no advance foremost if it is not so reliable.  

Guido

[chericks1]

Hi Guido,

I'm beginning to wonder why you are scanning (an automated procedure), but still performing a manual adjustment and calibration.  Don't take that the wrong way, you can do that.  It'll work.  I'm just wondering why.  I know that performing a scan reduces the switching code footprint (the amount of switching code) for this application.  Are there other advantages of performing a scan over making software calls in a For Loop?

I suggest that instead of using a scan list, an alternative could be to use a For Loop and change your inputs to the DAQmx Switch Connect or niSwitch Connect Channels VI during each iteration of the loop.  This method would allow you to take advantage of the Switch Soft Front Panel; it showing the module's state after each switching operation.

Thoughts?

Chad Erickson

Switch Product Support Engineer

NI - USA

[kudigu]

Hi Chad,

maybe more details will help to understand: We are measuring the power in for example 100 cycles. After each cycle the system performs a trigger which we want to use for switching the channel. During the measurement we have to check and adjust the power because it can change between some cycles.

The time between cycles can differ so we using the trigger and not fixed loop times.

A more sufficient way would be to measure the power on all channels parallel of course. But we need to use the equipment we already have.

I am thinking about a solution similar to your idea: to recieve the trigger separately and using the Event structure and niSwitch Connect Channels VI for switching while checking the status on the SSFP.

Thanks,

Guido

[chericks1]

Hi Guido,

Your solution should work.  Do you have any available hardware that can accept an input trigger?  However you decide to proceed, I would appreciate it if you could update this post.  Your efforts will assist future customers in developing similar applications.

Best regards,

Chad Erickson

Switch Product Support Engineer

NI - USA