Specifications

15
Additional Functions Section 2-5
2.4 Data Types
User references are bit, byte, or word-structured.
Reference type Sign Orientation
Discrete Inputs %I Bit / Byte
Discrete Outputs %Q Bit / Byte
Temporary Coils %T Bit / Byte
Internal Coils %M Bit / Byte
System Status References %SA, %SB, %SC, %S Bit / Byte
Discrete Globals %G Bit / Byte
Analog Inputs %AI Word / Double word
Analog Outputs %AQ Word / Double word
Registers %R Word / Double word
The size of each reference area is governed by the size of the PLC’s CPU.
2.5 Additional Functions
In addition to the random write and read access to PLC variables, a memory area
comprising 11 or 12 bytes is specified in the application definition as poll area. The
location of this memory area is specified in the application definition.
Only marginal conditions regarding this memory area:
- the PLC must be able to access in bit-mode and the SNP in byte-mode
- the memory area must be contiguous.
Byte-structured Memory Mapping
The data area comprises a maximum of 11 bytes
The start address must be located on a physical byte boundary.
The following start addresses are possible in accordance with (8 * n) + 1 ; n =
0, 1 , 2 : M1, M9, M17.
Example: Cyclic Data starts at %M1
MSB Description LSB
%M8 Write Coordination Byte %M1
%M16 Message Channel Low byte %M9
%M24 Message Channel High byte %M17
%M32 LED 1 to 4 %M25
%M40 LED 5 to 8 %M33
%M48 LED 8 to 12 %M41
%M56 LED 13 to 16 %M49
%M64 LED 17 to 20 %M57
%M72 LED 21 to 24 %M65
%M80 LED 25 to 28 %M73
%M88 LED 29 to 32 %M81
Word-structured Memory Mapping
The data area comprises a maximum of 6 words or 12 bytes.