Problem with clocked analogue DAQ

[Alan D]

hi everybody,
I am using an external channel to clock an analogue data aquisition. However, I have found that when this external channel frequency increases to above a certain level, the channels that are scanned are not scanned at the same frequency but lower. e.g. if the clock channel were 20Hz there would only be 15 samples logged per second (note this is only an example). Could anyone tell me why this is happening?
thanks for your help.
Alan

[Bob_Preis]

Suppose your scan clock period is Ts and channel clock period is Tc, then n*Tc (n = number of channels) must be smaller than Ts for all channels to be acquired within a scan.

Ensure n*Tc < Ts first.