Modbus addressing kind

[Kortex-CR]

It is not possible to define the nature of Modbus addressing zones, i.e. whether server addressing is performed on 5 digits (as is the case with most basic PLCs) or 6 digits (full range for advanced controllers).

5 digits addressing:
Coil or Register Number | Protocol Data Offset | Table Name
00001 - 09999 | 0000h-270Eh | Output coils
10001 - 19999 | 0000h-270Eh | Discrete inputs
30001 - 39999 | 0000h-270Eh | Input registers
40001 - 49999 | 0000h-270Eh | Holding registers

6digit addressing:
Coil or Register Number | Protocol Data Offset | Table Name
000001 - 065536 | 0000h-FFFFh | Output coils
100001 - 165536 | 0000h-FFFFh | Discrete inputs
300001 - 365536 | 0000h-FFFFh | Input registers
400001 - 465536 | 0000h-FFFFh | Holding registers

[sanny32]

The question is, why is it necessary to separate addresses into 5-digit and 6-digit ones, if 6-digit ones completely cover the address space of 5-digit ones?

[Kortex-CR]

Hello, this could allow you to emulate field controllers that only have a 5-digit address zone. If the client (for example, a SCADA system) is incorrectly configured, this can be detected using the Modbus error code returned to the client. I agree that this isn't THE essential feature when you understand the register zones identified in your specifications. Regards. Le mer. 8 oct. 2025 à 08:26, Alexandr Ananev ***@***.***> a écrit :

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*sanny32* left a comment (sanny32/OpenModSim#50) <#50 (comment)> The question is, why is it necessary to separate addresses into 5-digit and 6-digit ones, if 6-digit ones completely cover the address space of 5-digit ones? — Reply to this email directly, view it on GitHub <#50 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ASH235H5T7EA2XMY6BZ2XNT3WSVCPAVCNFSM6AAAAACIGMHBOSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGNZZHA3DQMZWGI> . You are receiving this because you authored the thread.Message ID: ***@***.***>