Allen-Bradley SLC 500 1746-NR4, User Manual

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Chapter 4
Preliminary Operating Considerations
4–2
The memory map shown in Figure 4.1 displays how the output and input
image tables are defined for the RTD module.
Figure 4.1
Memory Map
Channel 0 Configuration Word
Channel 1 Configuration Word
Channel 2 Configuration Word
Channel 3 Configuration Word
Channel 0 Data Word
Channel 1 Data Word
Channel 2 Data Word
Channel 3 Data Word
Channel 0 Status Word
Channel 1 Status Word
Channel 2 Status Word
Channel 3 Status Word
Output Image
8 Words
Input Image
8 Words
Output Image
Input Image
Output
Scan
Input
Scan
Output Image
Input Image
Slot e
Slot e
SLC 5/0X
Data Files
RTD Module
Image Table
Bit 15 Bit 0
Bit 15 Bit 0
Word 0
Word 1
Word 2
Word 3
Word 7
Word 0
Word 1
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
Address
Address
O:e.0
O:e.1
O:e.2
O:e.3
O:e.7
I:e.0
I:e.1
I:e.2
I:e.3
I:e.4
I:e.5
I:e.6
I:e.7
(Class 1)
Word 4 O:e.4
Word 5 O:e.5
Word 6
O:e.6
User–set Lower Scale Limit Range 0
User–set Upper Scale Limit Range 0
User–set Lower Scale Limit Range 1
User–set Upper Scale Limit Range 1
Output Image – Configuration Words
The 8–word, RTD module output image (defined as the output from the CPU
to the RTD module) contains information that you configure to define the
way a specific channel on the RTD module will work. These words take the
place of configuration DIP switches on the module. Although the RTD
output image is eight words long, only output words 0–3 are used to define
the operation of the module; output words 4–7 are used for special user–set
scaling using the proportional counts data format. Each output word 0–3
configures a single channel.
Example – If you want to configure channel 2 on the RTD module located in
slot 4 in the SLC chassis, your address would be O:4.2.
O : 4 . 2
File Type
Slot
Word
Element
Delimiter Word
Delimiter
Chapter 5, Channel Configuration, Data, and Status, gives you detailed bit
information about the data content of the configuration word.
Module Addressing
AB Spares