Multiple Devices driving 1 trigger line (or connecting lines)

[mimomar]

Hey all,

Here's what i've been trying to do recently and am starting to get frustrated. So basically I want multiple devices to drive the same trigger line. Thought this mighyt be a problem for my application. Let me rephrase with a question that would give me the optimal solution. I have an PXI-6653 card on my PXI-1045 and what i want to do is say:

Send triggers generated on 2 lines (say PXI_Trig0 and PXI_Trig1) to a 3rd line (say PXI_Trig2). effectively I want the line PXI_Trig2 to get triggered whenever either of the first 2 get triggered. (If you want to think of this in a binary logic way, I want something like "Trig2 = Trig0 OR Trig1" , so I will get a rising edge on 2 whenever 0 or 1 have a rising edge)..

 If it try to send (connect) both Trig0(source) and Trig1(source) to Trig2(destination) using NISYNC vi's, it wont work because it will say that Trig2 is already in use after connecting to one of the others (0 or 1).

Note that I dont want Trig0 or Trig1 to change, i.e i dont want to send trig0 to trig1 and then send trig1 to trig2

PS: when i say "send trig1 to trig2" i mean connect trig1 as the source and trig2 as the destination in the NISYNC connect trigger terminal VIs.

What can be done about this? Smart workarounds? or some way of overriding the fact that i cant connect multiple lines to the same destination line??

[Lars_L]

Hey mimomar,

Could you give us a little more background as to why you are trying to share the connection between these trigger lines? Most likely you will have to implement some sort of external connection to achieve this, but if I had more details as to the hardware that you are trying to synchronize with this setup then we should be able to give you the best solution. Let me know!

Also, it looks like you posted this in the LabVIEW forum as well. Since this issue deals primarily with the PXI hardware and how to best control this within LabVIEW let's keep this discussion in the PXI forum for the time being.

Regards,

Lars 

[mimomar]

hey,

I have some sort of a multi-user MIMO wireless communication setup. consisting of 3 TX's and 3 RX's (so PXI-5660's and 5670's). and i want the RX's to detect the packets from all users that will be transmitting basically one right after the other, each of them generating a trigger or marker even that i can export on to a different trigger line (i cant have all TX's generate triggers on the same line). So i pretty much wanted to aggregate all these triggers onto one line and use that line to trigger data acquisition at the receivers.

Thanks,

[S_Hong]

Hi Mimomar,

Unfortunately, none of our hardware can be configured for multiple trigger sources and therefore, I am afraid that without any external circuitry to perform the OR operation, you may not be able configure the behavior you are looking for. Now that being said, if you do decide to use an external circuit for your trigger, you may be able to compensate for the extra delay in your trigger circuitry by increasing your number of pre-trigger samples.

Another suggestion may be to reconfigure your task after every acquisition for the next trigger. So assuming that you know which RFSG is going to send the trigger, you can reconfigure your task's trigger source in a specific order after every acquisition.

I hope this helps,

Regards,