Counter and timer boards are programmable computer cards that perform digital counting and/or timing functions. Typically, they plug into slots onto motherboards or connect as serial or parallel devices. Counter and timer boards can generate pulse width modulated (PWM) signals for motor speed control, count the number of times a switch toggles, and count pulses from a motor wheel encoder disk. Pulses or toggles increment counters, which can advance forward, backward, or both forward and backward. Counter and timer boards also generate timed interrupts for analog-to-digital data acquisition and provide fine resolution timing. They are used to measure system latency, time software, and monitor product conveyor lines.