Advantech PCI-1710 Counter Operating Modes, Mode 0 Stop on Terminal Count, Mode 2 Rate Generator

A.3 Counter Operating Modes

MODE 0 – Stop on Terminal Count

The output will initially be low after you set this mode of operation. After you load the count into the selected count register, the output will remain low and the counter will count. When the counter reaches the terminal count, its output will go high and remain high until you reload it with the mode or a new count value. The counter continues to decrement after it reaches the terminal count. Rewriting a counter register during counting has the following results:

1.Writing to the first byte stops the current counting.

2.Writing to the second byte starts the new count.

MODE 1 – Programmable One-shot Pulse

The output is initially high. The output will go low on the count following the rising edge of the gate input. It will then go high on the terminal count. If you load a new count value while the output is low, the new value will not affect the duration of the one-shot pulse until the succeeding trigger. You can read the current count at any time without affecting the one-shot pulse. The one-shot is retriggerable, thus the output will remain low for the full count after any rising edge at the gate input.

MODE 2 – Rate Generator

The output will be low for one period of the input clock. The period from one output pulse to the next equals the number of input counts in the counter register. If you reload the counter register between output pulses, the present period will not be affected, but the subsequent period will reflect the value.

56 PCI-1750 User's Manual