The Allen-Bradley 1771-IK is a discontinued encoder/counter module assembly from the PLC-5 family. It is designed to interface with position and speed sensing devices using 12–24V DC signals. The module provides high-speed counting capabilities for use in motion control and automation systems. It fits into a standard 1771 I/O chassis and is compatible with Allen-Bradley programmable logic controllers. The 1771-IK supports block transfer instructions for efficient data communication between the module and the processor.