Target : I want to use wincc as upper machine through the modbus - rtu down a machine readings; Between the lower machine and wincc has a 485 turn Ethernet module,
The problem of : wincc PC to read the device ID is 1; Register address is 00 00; Register number of 00 05, CRC for 85 C9.
So that wincc send data for 03 01 00 00 0 05 85 C9, I used the modbus slave under a machine simulation software, this time under a machine data to the wincc, that's right,
Then I might be graffed in the next my next machine, inside a piece of code is matching 03 01 00 00 0 05 85 C9, arguably also can return data, but did not respond to a PC, and then I found after online debugging, lower their data instead of the above 03 01 1 a 81 00 01 D3 3 a, in order to determine and I use data from the wincc serial debugging assistant, discovery is 03 01 1 a 81 00 01 D3 3 a,
Finally feel good halo, 1, why is simulated under a machine modbus slave return data, under the real machine can not,
2, why send data changes the wincc, not expecting 03 01 00 00 05 85 C9,

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If I send the wrong area