Measurement Computing Personal Daq/3000 Series - Manual (Page 47)

Timing Mode
TIP: When using a counter for a trigger source, it is a good idea to use a pre-trigger with a value of at least 1.
The reason is that all counters start at zero with the initial scan; and there will be no valid reference in regard to
rising or falling edge. Setting a pre-trigger to 1 or more ensures that a valid reference value is present, and that
the first trigger will be legitimate.
This mode provides a means of measuring time between two subsequent events, i.e., the edge of one
channel with respect to the edge of another channel. The edge selection is done in each channel’s
debounce setup. Whenever the time measurement is latched from the counter, the counter is immediately
cleared and enabled for accepting the subsequent time period, which starts with the next edge on the main
channel.
Timing Mode
*There is one asynchronous read strobe for each of the four counter channels.
Note 1: Tick-sizes are: 20.83ns, 208.3ns, 2083ns, and 20833ns, derived from the 48 MHz system clock.
Personal Daq/3000 Series User’s Manual 887894 Counter Input Modes 5-13