A S S e r i e s O p e r a t i o n M a n u a l5 - 2_55.1 Introduction of DevicesThis section describes the values and strings processed by the PLC. It also describes the functions of devicesthat include input, output, and auxiliary relays, as well as timers, counters, and data registers. The PLCsimulates external devices in the PLC’s internal memory, so the word “device” is a generic name that refers toall the internal memory locations in the PLC. A device can be a bit device or a word device. Bit devicessimulate coils, contacts and flags, while word devices simulate registers.5.1.1 Device TableType Device name Number of devices RangeBit deviceInput relay X 1024 X0.0–X63.15Output relay Y 1024 Y0.0–Y63.15Data registerD 48,0000 D0.0–D29999.15W 48,0000 W0.0–W29999.15 *4Auxiliary relay M 8192 M0–M8191Special auxiliary relay SM 4096 SM0–SM4095Stepping relay S 2048 S0–S2047Timer T 512 T0–T511Counter C 512 C0–C51132-bit counter HC 256 HC0–HC255Word deviceInput relay X 64 X0–X63Output relay Y 64 Y0–Y63Data registerD 30000 D0–D29999W 30000 W0–W29999 *4Special auxiliary relay SR 2048 SR0–SR2047File register FR 65536 FR0–FR65535Timer T 512 T0–T511Counter C 512 C0–C51132-bit counter HC 256（512 words） HC0–HC255Index register E10 E0–E95 E10–E14 *4Constant*1 Decimal system K16 bits: -32768 to 3276732 bits: -2147483648 to 2147483647
