Fieldbus Appendix - ANYBUS®-S Modbus RTU DOC. ABS-APPENDIX-RTU Rev 1.00 2003-04-28
5 Functions & Operation
5.1 Memory map structure of the Modbus RTU Module
5.1.1 DPRAM IN/OUT Data Areas
DPRAM Address |
Contents |
Access |
Modbus address |
|
|
|
|
|
|
|
|
IN area |
|
|
|
|
|
|
|
000h |
- 01FFh |
Input data area ; |
R/W |
0001 - 0256 |
|
|
512 bytes |
|
|
|
|
|
|
|
|
|
OUT area |
|
|
|
|
|
|
|
200h |
- 3FFh |
Output data area; |
R/O |
1025 - 1280 |
|
|
512 Bytes |
|
|
|
|
|
|
|
Table 16: DPRAM IN/OUT data areas
The application exchanges data with the fieldbus via the DPRAM IN and OUT data areas. Prior of using the module, the length of the IN and OUT areas have to be defined. This is accomplished through initializing the module (please see chapter 6.5). The AnyBus-S has the possibility to use both fast data and slow data, but all data transferred on the Modbus RTU Fieldbus is to be considered as fast data. Thus, the configuration of the IN and OUT areas are very simple.
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