Chapter 2 Devices Table of Contents 2.1 Introduction of Devices..............................................................................2-2 2.1.1 Devise List..........................................................................................2-2 2.1.2 Basic Structure of I/O Storages..........................................................2-3 2.1.3 Relation between the PLC Action and the Device Type.....................2-3 2.1.4 Latched Areas in the Device Range...................................................2-3 2.2 Functions of Devices .................................................................................2-4 2.2.1 Values and Constants ........................................................................2-4 2.2.2 Floating-point Numbers......................................................................2-6 2.2.2.1 Single-precision Floating-point Numbers ....................................2-6 2.2.2.2 Double-precision Floating-point Numbers ...................................2-6 2.2.2.3 Decimal Floating-point Numbers.................................................2-7 2.2.3 Strings................................................................................................2-8 2.2.4 Input Relays .......................................................................................2-9 2.2.5 Output Relays ....................................................................................2-9 2.2.6 Auxiliary Relays..................................................................................2-9 2.2.7 Special Auxiliary Relays...................................................................2-10 2.2.8 Refresh Time of Special Auxiliary Relays.........................................2-34 2.2.9 Stepping Relays ...............................................................................2-44 2.2.10 Timers ..............................................................................................2-44 2.2.11 Counters...........................................................................................2-46 2.2.12 32-bit Counters.................................................................................2-47 2.2.13 Data Registers .................................................................................2-49 2.2.14 Special Data Registers.....................................................................2-49 2.2.15 Refresh Time of Special Data Registers ..........................................2-73 2.2.16 Additional Remarks on Special Auxiliary Relays and Special Data Registers..........................................................................................2-75 2.2.17 Link Registers ..................................................................................2-88 2.2.18 Index Registers ................................................................................2-88