7.4.4 Frequency Converter Address (ADR)Two different address formats are used.The address range of the frequency converter is either 1–31 or 1–126.1. Address format 1–31:Bit 7=0 (address format 1–31 active)Bit 6 is not usedBit 5=1: Broadcast, address bits (0–4) are not usedBit 5=0: No BroadcastBit 0–4=frequency converter address 1–312. Address format 1–126:Bit 7=1 (address format 1–126 active)Bit 0–6=frequency converter address 1–126Bit 0–6=0 BroadcastThe follower returns the address byte unchanged to themaster in the response telegram.7.4.5 Data Control Byte (BCC)The checksum is calculated as an XOR-function. Before thefirst byte in the telegram is received, the CalculatedChecksum is 0.7.4.6 The Data FieldThe structure of data blocks depends on the type of telegram. There are 3 types, and the type applies for both controltelegrams (master⇒follower) and response telegrams (follower⇒master).The 3 types of telegram are:Process block (PCD)The PCD is made up of a data block of 4 bytes (2 words) and contains:• Control word and reference value (from master to follower)• Status word and present output frequency (from follower to master)ADRLGESTX PCD1 PCD2 BCC130BA269.10Illustration 7.7 PCDParameter blockThe parameter block is used to transfer parameters between master and follower. The data block is made up of 12 bytes (6words) and also contains the process block.PKE INDADRLGESTX PCD1 PCD2 BCC130BA271.10PWEhigh PWElowIllustration 7.8 Parameter BlockText blockThe text block is used to read or write texts via the data block.PKE IND130BA270.10ADRLGESTX PCD1 PCD2 BCCCh1 Ch2 ChnIllustration 7.9 Text BlockRS-485 Installation and Set... Design GuideMG20Z202 Danfoss A/S © Rev. 06/2014 All rights reserved. 1517 7
