Making another counter VI for usb-6008 using Labview 8.5

[Diaa Abidou]

I want to create another counter for usb-6008 using Labview 8.5 as it is needed to calculate two speeds simultaneously.

[Now_With_Underscores]

The cheapest way to do this would be to purchase another USB-6008.  The counter is a built in hardware feature of DAQ devices.  You could purchase external counter circuitry and then interface that through the DIO ports as a word, but this is a lot of work and is probably outside of typical support.

[Diaa Abidou]

So, there is no way to create something can count the input digital edges using Labview ?

Anyway, thanks for your attention and help. 

[Now_With_Underscores · Accepted solution]

The best way to do this is to use the counter.  The counter counts signals without having to interrupt the system or use the USB bus.  When you request the number of ticks that the counter has seen, a request is thrown from the CPU to the USB line to the 6008, which then asks the counter "How many ticks have you seen?"  That number is returned over the USB bus, goes to the CPU, and then displays on your screen.  Since the DIO lines on the 6008 are software timed, there is no way to guarantee that the data returning to the CPU is deterministic.  The conceptual difference between software-controlled DIO (which nondeterministically returns an entire data stream) and a software-tick-request-controlled counter (which returns a single number with the number of ticks) prevents us from using the DIO lines on the 6008.  The cheapest way to count more edges is to purchase more 6008s.  Another possibility would be to purchase a PCI counter board such as the PCI-6602, which has 8 counters. The most counters we offer in the USB form factor is 2 per device.

[Diaa Abidou]

Thanks. I think thats enough.