The Eaton Cutler-Hammer D100CAA20 is a 20 I/O Micro PLC from D100 series. This is a micro-programmable controller with an outstanding feature of the hand-held programmer with LCD display. Other features of the D100CAA20 are 20 I/O (12 pieces of 115 Volts AC inputs, 8 pieces of triac 115 Volts AC outputs), built-in PROM write, programming functions (timers, counters, master control, jump, one-shot, step sequence and flip-flop). It does not have HSC or analog capabilities, but it can support up to 16 timers, 16 counters, 128 steps of shift registers, 256 steps of step sequencers. This module’s scan time per 1K memory is 8 milliseconds, its memory size is 1K RAM, and this module is a stand-alone device. All that is needed to complete the system is to connect it to the 115 Volt AC power source, connect inputs and outputs to appropriate terminals, enter a program, and the system is ready to go. The program can be entered by plugging in a pre-programmed PROM into the controller, connecting a hand-held programmer and keying in the program or by connecting to a PC and entering the program from the computer keyboard. The D100CAA20 is part of a modular D100 PLC family, which can put together controllers with expanding modules to meet a full range of requirements for small PLCs. This controller can be expanded with up to two modules and it is capable to incorporate maximum 40 I/Os (24 inputs + 16 outputs). A hand-held programmer is a device generally used for programming purpose of the D100CAA20 PLC. It is plugged into the controller and receives power from it. The program is written in RAM memory and it can be saved to a PROM module. Computer programming can also be achieved by using D100CCS60 5.25-inch disk software or D100CCS35 3.25-inch disk software. These programs permit programming, monitoring, troubleshooting and reporting from a PC. The D100CAA20 controllers work best in an ambient temperature range maintained at 0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit). This controller can be directly mounted to the panel with screws or to DIN rails. The product’s dimensions are 9.4 x 4.0 x 4.4 inches (240 x 100 x 112 millimeters).