2-1 
Chapter 2  Devices 
 
Table of Contents 
2.1  Introduction of Devices ............................................................................. 2-2 
2.1.1  Devise List ......................................................................................... 2-2 
2.1.1.1 AH500 Basic CPU Modules (AHCPU500/510/520/530) ................... 2-2 
2.1.1.2 AH500 Advanced CPU Modules (AHCPU501/511/521/531) ........... 2-3 
2.1.2  Basic Structure of I/O Storages ......................................................... 2-4 
2.1.3  Relation between the PLC Action and the Device Type .................... 2-4 
2.1.4  Latched Areas in the Device Range .................................................. 2-5 
2.2  Functions of Devices ................................................................................ 2-6 
2.2.1  Values and Constants ....................................................................... 2-6 
2.2.2  Floating-point Numbers ..................................................................... 2-7 
2.2.2.1  Single-precision Floating-point Numbers ................................... 2-7 
2.2.2.2  Double-precision Floating-point Numbers .................................. 2-8 
2.2.2.3  Decimal Floating-point Numbers ................................................ 2-9 
2.2.3  Strings ............................................................................................... 2-9 
2.2.4  Input Relays .....................................................................................2-10 
2.2.5  Output Relays ..................................................................................2-11 
2.2.6  Auxiliary Relays ................................................................................2-11 
2.2.7  Special Auxiliary Relays ...................................................................2-12 
2.2.8  Refresh Time of Special Auxiliary Relays .........................................2-38 
2.2.9  Stepping Relays ...............................................................................2-46 
2.2.10  Timers ...........................................................................................2-47 
2.2.11  Counters .......................................................................................2-48 
2.2.12  32-bit Counters .............................................................................2-50 
2.2.13  Data Registers ..............................................................................2-51 
2.2.14  Special Data Registers .................................................................2-52 
2.2.15  Refresh Time of Special Data Registers .......................................2-80 
2.2.16  Additional Remarks on Special Auxiliary Relays and Special Data 
Registers .......................................................................................2-82 
2.2.17  Link Registers ...............................................................................2-98 
2.2.18  Index Registers .............................................................................2-98