accurate time delay of 100ns

[andreastanner]

Good morning everbody,

it is me again; still in trouble with the counters of the PCI 6601. I am using the software Labview 8.0 and within

this software one DAQ assistant to control the four counters. All counters work are 32 bit, 20 Mhz counters.

I am trying to send out 4 pulses (one on each output channel of one counter). The pulses have a high time of about

50 us and are low otherwise. I am trying to implement a time delay with an accuracy of at least 1 us between these pulses. At an frequency of

20 MHz, this should not be a problem (50 ns resolution!!!).

For some reason, LabView screws it up and on my oscilloscope I see UNPROGRAMMED time delays of 7us up to 21 us.

It seems there is time delay of about 7us from channel to channel....

Can anybody help me out, please?

Thanks a lot,

Andreas Tanner

[Kevin_Price]

The 4 outputs need to be synchronized so that the pulses start their timekeeping from the same t=0 point.  Your counter tasks should all be configured to start on the same digital trigger signal, and the tasks should all be started before the trigger event.

I've made a habit of generating the trigger signal with digital bit DIO 0.  The counters can view this signal as a trigger by referring to it as PFI0.  This saves me having to do any wire-and-screwdriver work.

Note: it is also possible to "cascade" the counters by having each one trigger the next, but a single common trigger is probably the simpler path forward.

-Kevin P.

[andreasta]

Hi Kevin,

thanks a lot for your help; I have set it up the way you described and it works
perfectly. Thanks again,
have a good day,

Andreas T.