Based on the summary specs, you're probably good up to 25 MHz. (Technically, the spec for external base clock frequency most closely maps to the counter's Source pin freq spec. I *think* but can't promise that the 25 MHz freq spec applies to any use of PFI pins routed to counter input pins.)
Please also note that there's a *big* distinction between the ability to *COUNT* accurately at up to 25 MHz and the ability of your system to *sample* at any particular rate. Unlike the typical analog acquisition task, you don't need to *sample* at 2x-10x the incoming frequency. I've quite commonly sampled at 0.01x.
Counter tasks play by different rules sometimes, because you aren't sampling the 25 MHz signal, you're sampling the internal hardware count register value. You generally don't need (or even want) to sample every increment of the count value.
-Kevin P
ALERT! LabVIEW's subscription-only policy came to an end (finally!). Unfortunately, pricing favors the captured and committed over new adopters -- so tread carefully.
