counters PCI 6602 80 MHz

[anneton]

This program I enclose within this question allows you to measure a TTL frequency using two counters in Visual Basic. One counter is configured to generate a single pulse. The other counter just counts while its gate (the other counter's output is high). You can specify the counters to use with a DAQ-STC, which is only 0 & 1. With an NI-TIO, the 2 counters should be in the same counter pair (0&1, 2&3, 4&5, 6&7), or you need to use an external wire to connect the output of counter a to the gate of counter b as well as use a Select_Signal to route the output of counter a to its output pin. Also for the NI-TIO, this example just uses either the 100 kHz or 20 MHz timebase to generate the pulse and selects one of the two based on a 24 bit count
er.
I would like to uses this example at 80Mhz for NI-TIO.
Could you write this example in LabView?Thanks.

[rgharrison]

Hi Anne,

This VB example is the same as the LabVIEW shipping example. You can get to the shipping example by selecting Help >> Find Examples... >> Hardware Input and Output >> Traditional DAQ >> Counters >> NI-TIO. This shipping example allows you to select "maximum" as the source of the second counter (which would be the 80MHz timebase) but then you wouldn't be measuring your signal. Essentially, you shouldn't need the 80MHz timebase if you are using 2 counters.

The way frequency measurement works is described nicely in the following Tutorial. The section of interest to you would be the "Measurement Error and 3 Frequency Measurement Methods".

Making Accurate Frequency Measurements
http://zone.ni.com/devzone/conceptd.nsf/webmain/CD2C8AAED8FA59A48625
6C230078FE75?opendocument

Hope that helps Anne. Have a good day.

Ron