ADLINK PCI-8124-C - Manual (Page 46)

36 Operation Theory
4.2.4 FIFO Mode
Continuous triggering is fulfilled by linear function and FIFO.
These two modes have their own comparators and can be used at
the same time. The FIFO mode is usually used on random com-
paring data condition. Users can preset these data into FIFO and
perform continuous triggering. Each FIFO has 1023 random com-
paring data space. If users have more random data than 1023, try
to polling FIFO empty status or wait interrupt event and refill reset
random data.
4.2.5 Timer Function
There are 4 timers on PCI-8124-C. The timer is started by TTL
input and the timer can be set to counters to simulate encoder
inputs. It can also output to trigger pins directly. The timer is
designed by a down-counter. Users must set a counter value into
timer for down counting. Once the timer counter reaches zero, the
timer will output a pulse to trigger pin or increase encoder counter
by 1. The down counting speed is 400ns and the maximum coun-
ter value is 14-bit.