SPLat/PC for dialects 16 or later (e.g. 7.16.0) supports the onboard quadrature counter with a special simulation window. You show this window with the menu selection Window>OBQC.

The window allows you to dial in a count rate up to 3kHz (realistic for 8-bit controllers such as the CC18, although 300kHz is more realistic for 32-bit controllers such as the DC216 and DT16), and have the counter count up or down or stop. When stopped you can also type a preset number of counts into the counter (green numbers). You will be prevented from entering invalid numbers.

When the counter is counting, it does so at a simulated rate that assumes each instruction simulated by SPLat/PC is taking 50 microseconds. That is a reasonable average figure for older (8-bit) SPLat controllers such as SL99, MS12 and MMi20x. (On 32-bit boards, the counting is done in hardware and is much faster.)

The simulator is not able to recognize and quadrature count actual hardware inputs during development mode, i.e when connected to a board.