Available. The Allen-Bradley 1771-IJ is an Encoder/Counter Module designed for use with Allen-Bradley PLC-5 controllers. This module maintains a count of input pulses from devices such as quadrature encoders, high-speed optical beam counters, and certain types of switches, independent of the processor. It can compare the count to preset values and activate outputs accordingly. The 1771-IJ operates with a 5V DC external power supply, allowing inputs to be TTL compatible. Outputs can be driven from the 5V DC supply through the module or from a separate load supply of a different voltage. The module supports counting in BCD (000 to 999) and binary (0000 to 4095) modes, with carry and borrow bits provided for cascading counters. It also offers modes to improve accuracy, such as counting both rising and falling edges of channel A (times 2 mode) or both channel inputs (times 4 mode). The maximum detectable input pulse frequency is 50 kHz. The 1771-IJ is compatible with any Allen-Bradley programmable controller employing the 1771 I/O structure.