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Modbus Rtu With Danfoss Fc102


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I'm trying to read and write some parameters from a Danfoss FC102 with a MODBUS RTU protocoll.

Unfortunatly i don't have the list with available MODBUS parameters for the Danfoss FC102.


Can someboby tell me where i can find the MODBUS-list? The Danfoss website did not help me out.




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Hello Marcel


Welcome to the forum.


I presume that the FC102 is the same as the FC202, in which case the information in the manuals is a little unclear and in some cases, misleading.


You must use MODBUS 6 digit addressing if you want to access all the registers, and typically the upper registers are the ones that you will want to read and write.


The addresses are made up of taking the Danfoss function number, multiplying by 1000 and adding 400000.

For example, to access 16.03, you take 16.03 x 1000 = 16030 then add 400000 to get 416030 and that is the six digit addressing.


If you do not have six digit addressing available, and your plc is not fully 5 digit compliant in that it lets you exceed 49999, then you can add 40000 instead so 16.03 would become 56030.


The control word can be accessed at 50.00 so with 6 digit addressing, this becomes 450000.


The only other issue that I have found is that some 16 bit data needs to be accessed as 32 or you get an error.

I would suggest adding one data field at a time to prove single word or double word access.


Best regards,


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