Danfoss VLT HVAC Drive FC 100 Series Design Manual

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Danfoss VLT HVAC Drive FC 100 Series Design Manual Manual pdf 130 page image

7.3. Network Configuration7.3.1. Frequency Converter Set-upSet the following parameters to enable the FC protocol for the frequencyconverter.Parameter Number Parameter Name Setting8-30 Protocol FC8-31 Address 1 - 1268-32 Baud Rate 2400 - 1152008-33 Parity/Stop bits Even parity, 1 stop bit (default)7.4. FC Protocol Message Framing Structure7.4.1. Content of a Character (byte)Each character transferred begins with a start bit. Then 8 data bits are transferred, corresponding to a byte. Each character is secured via a parity bit,which is set at "1" when it reaches parity (i.e. when there is an equal number of 1’s in the 8 data bits and the parity bit in total). A character is completedby a stop bit, thus consisting of 11 bits in all.7.4.2. Telegram StructureEach telegram begins with a start character (STX)=02 Hex, followed by a byte denoting the telegram length (LGE) and a byte denoting the frequencyconverter address (ADR). A number of data bytes (variable, depending on the type of telegram) follows. The telegram is completed by a data controlbyte (BCC).7.4.3. Telegram Length (LGE)The telegram length is the number of data bytes plus the address byte ADR and the data control byte BCC.The length of telegrams with 4 data bytes is LGE = 4 + 1 + 1 = 6 bytesThe length of telegrams with 12 data bytes is LGE = 12 + 1 + 1 = 14 bytesThe length of telegrams containing texts is 10 1)+n bytes1) The 10 represents the fixed characters, while the “n’” is variable (depending on the length of the text).7. RS-485 Installation and Set-up VLT® HVAC Drive Design Guide130 MG.11.B7.02 - VLT® is a registered Danfoss trademark7