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| 2/13/2008 1:37 PM | |
Joined: 9/27/2006 Last visit: 2/6/2025 Posts: 12333 Rating:
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Hello druim; In the modsla_e.pdf manual chapter 8 is dedicated to explain the correspondance between the modbus address requested by the Master and the internal S7 address used by the CP341 slave. If you look on page 72 and following, you will discover the calcs used to switch for an address requested for function 3 (Modbus master); the base DB address for this Modbus function is DB800, each DB limited to 127 registers (words). In your user program, you must place (MOV) your data in the base registers(DB800,DBB0) at the correct offset so the master's request can be coordinated with the data the slave is providing in response to a function 3 call.. For Modbus Function 4, the base DB is DB900. Then you must calculate the offset register corresponding to the start register address of the master request. The math is well explained, so take a few minutes to understand the process and work through the example calculations. Then everything should become clear. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 13.02.2008 13:38 |
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| 2/13/2008 5:03 PM | |
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Posts: 3 Rating:
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Fantastic dchartier!!!!! That isall whatI want!!!!! Perfect. Thankyou very much! |
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