Modbus for residential D24810 User manual(A007)

1Introduction
TheunitworksasaModbusslaveandcompliedwithMODBUSoverseriallinespecicationand
implementationguideV1.0ifnothingelseismentioninthismanual.
2Transmissionmodes
ModbusRTU.
Supportedfunctioncodes:
1:ReadCoils
2:ReadDiscreteInput
3:ReadHoldingRegister
4:ReadInputRegister
5:WriteSingleCoil
6:WriteSingleRegister
15:WriteMultipleCoils
16:WriteMultipleRegisters
3Physicallayer
TwowireRS-485.
Thesupportedcommunicationparametersare:
9600Bdor19200Bd.
Noparity,evenparityoroddparity.
4Address
Slaveaddress1to247.
Thefollowingexceptioncodesaregeneratedbytheslave:
1.ILLEGALFUNCTION:whenusinganyofthefunctionscodenotlistedabove.
2.ILLEGALDATAADDRESS:whenaddressinganyregister,coilordigitalinputhigherthanthehighest
addressorlowerthanthelowestaddress.
3.ILLEGALDATAVALUE:whentheformatoftheModbusmessageisfaulty(e.g.wrongmessagelength).
5Notes
Coilsanddigitalinputsarealwaysavailableasregisteraswell.Theaddressofthecoilordigitalinput
canbecalculatedasfollows:
Address(RegisterAddress*16)15
Readinganyregisters,inputsorcoilsthatarenotmentionedinthetablesbelowwillresultinreading0.
Writingtoanyaddressthatisnotlistedaswriteableinthetablesbelow,orisnotlistedatall,willhaveno
effect.
Addressinganyregister,coilordigitalinputhigherthanthehighestaddresswillresultinerror02,“Illegal
DataAddress”intheModbusresponse.
ModbusforResidentialunitsUserManual
D24810
1
SystemairSverigeAB