PCI-6534 REQ/ACK

[pcevasco]

I have two signals:
- (signal_1) a pulse train with a fixed pulse width (1us) and a fixed period (1ms)
- (signal_2) a separate data line that has serial data on it after every pulse.

I would like to use signal_1 to trigger (rising or falling edge) an acquisition of signal_2 for a fixed number of samples, continuously. For example, signal_1 would trigger the acquisition of 100 samples of signal_2. The acquisition would then stop and wait for the next pulse on signal_1.

So far I can either acquire the data continuously (but the acquisition is not triggering off of signal_1) or I can trigger a single acquisition only.

What pins should I connect signal_1 and signal_2 to? Do I need a third signal to start and stop the acquisition? Which Labview
VIs would pertain to this type of an acquisition?

Thanks

[nickbike]

Hello,
When using the PCI-6534, configuring start and stop triggering is only valid for finite input operations.
With that said, there is another option you can do with the PCI-6534 that you might be able to use.

Use an internal clock for sample timing, and use (signal_1) as a handshaking line. This is called burst mode handshaking. This type of acquisition is based on an internal clock, but can be paused at anytime but either the ACK(local) or REQ(remote)lines. When both ACK and REQ are at a predetermined state, data will be latched.
You can find examples here and search for "burst mode". This sounds like it would require that your (single_1) be changed to stay high or low while
the data is being latched or you could use the third signal that you mentioned.

Here is link to a tutorial on digital I/O.

Nicholas C
National Instruments
Applications Engineering