Available. The Mitsubishi A1SD61 is a high-speed counter module designed for the MELSEC-A Series programmable logic controllers (PLCs). This module offers a single channel capable of handling both 1-phase and 2-phase input signals at 5, 12, or 24 VDC, with a maximum counting speed of 50,000 pulses per second (pps) for 1-phase inputs and 7,000 pps for 2-phase inputs. It features a 32-bit binary counter with a range from -2,147,483,648 to 2,147,483,647, and includes UP/DOWN preset counter and ring counter functions. The module provides external inputs for preset and function start, and external outputs for coincidence signals, all with specified voltage and current ratings. Designed for integration with Mitsubishi's MELSEC-A Series PLCs, the A1SD61 ensures efficient and reliable high-speed counting operations in industrial automation applications.