The counter structure is similar to that of the timer because it also has a preset and accumulator value, also called PRE and ACC.
There are several bits that are set by the counter, including:
CU for counting up,
CD for counting down,
DN to indicate that the counter has reached the preset value,
OV to indicate an accumulator overflow situation,
UN to indicate an accumulator underflow situation,
UA is used only with high-speed counter I/O and indicates the accumulator is updating.
There are various instructions that are used for timers and counters, including timer on and timer off instructions and up and down counter instructions.