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2570 Synchronise with LIN card

I have a LIN 3072 PXI card which is capable of outputting a 5v trigger pulse when a specific LIN frame occurs.
What I would like to do is connect this trigger output back in to my PXI 2570 relay card to close a specific relay for a period of time, the idea being to examine how a DUT responds to multiple interrupts happening simultaneously.

The documentation for the 2570 relay card mentions a trigger input but this only seems to be a trigger on the PXI bus and there is no other trigger pin I can locate on the front connector.

How can I connect this trigger signal to close my relays ?

Thanks,
Mike


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Dear Mike,

The best way forward is likely to be investing in another PXI card that will allow you to produce a retriggerable pulse train – the card can be fairly simple, as long as it gives you access to a counter. You could then route the counter to the trigger line of the relay card via the PXI bus. This method purely uses hardware timing – so you can achieve high levels of precision.

You will also need to define a scan list. Once a pulse has been received your application will step through to the next item on the switch scan list (therefore making a new relay and breaking the one currently being used).

Search “scanning” in the LabVIEW example finder, and you will be greeted with plenty of helpful example VIs. I would recommend having a look at the “niSwitch Software Scanning.vi”.

>> This is all assuming that you have niSwitch installed <<

There is plenty of information on our website concerning creating scan lists and the use of the switch software.

What sort of timing specs do you require?? If you can afford to carry out the timing within software (so you can tolerate an error of, say, +/- 100ms) then you could use any old data acquisition card to read the 5V trigger, and to allow you application to produce a software trigger which can be fed to you relay board via the software trigger line on the PXI bus.

Just to confirm… there is no external triggering line. Triggering is exclusively carried out by routing signals through the back plane of the PXI chassis.

I hope this has been of some use to you,

Best wishes

Rich Roberts
Senior Marketing Engineer, National Instruments
Connect on LinkedIn: https://www.linkedin.com/in/richard-roberts-4176a27b/
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Hi Rich,

Thanks for your reply.
I have some other PXI cards in the chassis, a 6052E and a 6733.
I think the 6733 might be most suitable as it has several PFI inputs on the front connector which I think can be used to trigger the PXI bus.
So correct me if I am wrong on this.
  • I connect the LIN 5v pulse to one of the PFI inputs.
  • I then setup the 6733 card to pulse the a PXI line every time it receives a LIN pulse.
  • My vi that controls the 2570 relay card monitors for this pulse and uses it to step through the scan list.
I would like to specify only one relay in the scan list and thus only pulse this one in sync with a LIN frame. Is this possible with scanning ?
The hardware solution is the best for my app as I need to be precise with the relay activation down to within 10ms.

Thanks for your help.
Mike
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Hey Mike,

 

Firstly, I apologise profusely for not getting back to you sooner. I have been away teaching for the past few days.

 

You have correctly interpreted my suggestion, although you have raised a very good question! Even though you are using a single relay you will need to implement some kind of scan list – there are 40 relays contained within the 2570 board, and so trigger lines could not be set up for each individual relay.

 

You should be able to create a workable scan list for a single item. If you are struggling with this, perhaps you could implement a scan list that switches between the relay you wish to open & close and a dummy relay. The dummy relay being one of the 39 unused relays within your module - interacting with this shouldn’t have any impact on your experiment.

 

Furthermore, there is plenty of information concerning scan list creation on the ni.com website.

 

Sorry again for the late reply, and thanks for your patience,

Best of luck with your application,

Rich Roberts
Senior Marketing Engineer, National Instruments
Connect on LinkedIn: https://www.linkedin.com/in/richard-roberts-4176a27b/
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Thats some good advice Rich. Very much appreciated.Smiley Happy

Best Regards,
Mike
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Hi Mike,
 
I read through this forum, and wanted to confirm that you will be successful in narrowing your precision to within 10 ms by following Rich's advice.  In fact, the time between rising edge of your trigger and relay actuation should be closer to around 5 ms.  If you are using LabVIEW, the DAQmx Signal Routing VIs (i.e. DAQmx Connect Terminals.vi) will allow you to connect a PXI-6733's PFI line (such as its counter source input) to a PXI Trigger line.  Then, as Rich mentioned, choose that particular trigger line to advance your PXI-2570's scan list. 
 
Within your scan list, you could have entries similar to the following to actuate the applicable relay upon a trigger:
/2570/nc0->com0;
/2570/no0->com0;
 
Please update the forum if you have any difficulties. 
 
Good luck and best regards!
 
Chad Erickson
Switch Product Support Engineer
NI - USA
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