modbus addressing query

[Guest novice]

hi ppl, i'm new to this pc and plc stuffs..recently started a project with s7 200 siemens plc. digital inputs i0.0 to i0.7 is being mapped to 010001 to 010008 in modbus. digital outputs q0.0 to q0.7 are mapped to 000001 to 000008 . where are the memry bits m0.0 to m31.7 mapped to?? is there any mapping between the plc and modbus master?? pls help me with regards to this.. i communicate with pc thru freeport in modbus. thnx in advance.

[khekd 2]

If you are using the modbus standard library in the microwin software you should have both the modbus init and slave blocks. Within the init block you have to define the Hold Start which can be a pointer with i.e. &MB0 and it will map to starting address 40001. If you are not using these library commands you can purchase this from your Siemens distributor for a nominal cost.