Danfoss VLT HVAC Basic Drive FC 100 Series Design Manual

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Danfoss VLT HVAC Basic Drive FC 100 Series Design Manual Manual pdf 76 page image

7.9.5 Conversion FactorThe different attributes for each parameter can be seen inthe section on factory settings. Since a parameter valuecan only be transferred as a whole number, a conversionfactor must be used to transfer decimals. Please refer tothe Parameters section.7.9.6 Parameter ValuesStandard Data TypesStandard data types are int16, int32, uint8, uint16 anduint32. They are stored as 4x registers (40001 – 4FFFF). Theparameters are read using function 03HEX "Read HoldingRegisters." Parameters are written using the function 6HEX"Preset Single Register" for 1 register (16 bits), and thefunction 10HEX "Preset Multiple Registers" for 2 registers(32 bits). Readable sizes range from 1 register (16 bits) upto 10 registers (20 characters).Non standard Data TypesNon standard data types are text strings and are stored as4x registers (40001 – 4FFFF). The parameters are readusing function 03HEX "Read Holding Registers" and writtenusing function 10HEX "Preset Multiple Registers." Readablesizes range from 1 register (2 characters) up to 10 registers(20 characters).7.10 ExamplesThe following examples illustrate various Modbus RTUcommands. If an error occurs, please refer to the ExceptionCodes section.7.10.1 Read Coil Status (01 HEX)DescriptionThis function reads the ON/OFF status of discrete outputs(coils) in the frequency converter. Broadcast is neversupported for reads.QueryThe query message specifies the starting coil and quantityof coils to be read. Coil addresses start at zero, i.e. coil 33is addressed as 32.Example of a request to read coils 33-48 (Status Word)from slave device 01.Field Name Example (HEX)Slave Address 01 (frequency converter address)Function 01 (read coils)Starting Address HI 00Starting Address LO 20 (32 decimals) Coil 33No. of Points HI 00No. of Points LO 10 (16 decimals)Error Check (CRC) -ResponseThe coil status in the response message is packed as onecoil per bit of the data field. Status is indicated as: 1 = ON;0 = OFF. The LSB of the first data byte contains the coiladdressed in the query. The other coils follow toward thehigh order end of this byte, and from ‘low order to highorder’ in subsequent bytes.If the returned coil quantity is not a multiple of eight, theremaining bits in the final data byte will be padded withzeros (toward the high order end of the byte). The ByteCount field specifies the number of complete bytes ofdata.Field Name Example (HEX)Slave Address 01 (frequency converter address)Function 01 (read coils)Byte Count 02 (2 bytes of data)Data (Coils 40-33) 07Data (Coils 48-41) 06 (STW=0607hex)Error Check (CRC) -NOTECoils and registers are addressed explicit with an off-set of-1 in Modbus.I.e. Coil 33 is addressed as Coil 32.7.10.2 Force/Write Single Coil (05 HEX)DescriptionThis function forces a writes a coil to either ON or OFF.When broadcast the function forces the same coilreferences in all attached slaves.QueryThe query message specifies the coil 65 (parameter writecontrol) to be forced. Coil addresses start at zero, i.e. coil65 is addressed as 64. Force Data = 00 00HEX (OFF) or FF00HEX (ON).Field Name Example (HEX)Slave Address 01 (frequency converter address)Function 05 (write single coil)Coil Address HI 00Coil Address LO 40 (64 decimal) Coil 65Force Data HI FFForce Data LO 00 (FF 00 = ON)Error Check (CRC) -RS-485 Installation and Set... VLT HVAC Basic Drive Design GuideMG.18.C2.02 - VLT® is a registered Danfoss trademark 757 7