Danfoss VLT AQUA Drive FC 202 Design Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

7.5 Examples7.5.1 Writing a Parameter ValueChange 4-14 Motor Speed High Limit [Hz] to 100 Hz.Write the data in EEPROM.PKE=E19E Hex - Write single word in 4-14 Motor Speed HighLimit [Hz]IND=0000 HexPWEhigh=0000 HexPWElow=03E8 Hex - Data value 1,000, corresponding to 100Hz, see chapter 7.4.12 Conversion.E19E HPKE IND PWE high PWE low0000 H 0000 H 03E8 H130BA092.10Illustration 7.12 TelegramNOTICE4-14 Motor Speed High Limit [Hz] is a single word, and theparameter command for write in EEPROM is “E.”Parameter number 4–14 is 19E in hexadecimal.119E HPKE IND PWE high PWE low0000 H 0000 H 03E8 H130BA093.10Illustration 7.13 Response from Master to Follower7.5.2 Reading a Parameter ValueRead the value in 3-41 Ramp 1 Ramp Up TimePKE=1,155 Hex - Read parameter value in 3-41 Ramp 1Ramp Up TimeIND=0000 HexPWEhigh=0000 HexPWElow=0000 Hex1155 HPKE IND PWE high PWE low0000 H 0000 H 0000 H130BA094.10Illustration 7.14 Parameter ValueIf the value in 3-41 Ramp 1 Ramp Up Time is 10 s, theresponse from the follower to the master is:130BA267.101155 HPKE IND0000 H 0000 H 03E8 HPWE high PWE lowIllustration 7.15 Response from Follower to Master3E8 Hex corresponds to 1000 decimal. The conversionindex for 3-41 Ramp 1 Ramp Up Time is -2.3-41 Ramp 1 Ramp Up Time is of the type Unsigned 32.7.6 Modbus RTU Overview7.6.1 AssumptionsDanfoss assumes that the installed controller supports theinterfaces in this manual, and strictly observes allrequirements and limitations stipulated in the controllerand frequency converter.7.6.2 Prerequisite KnowledgeThe Modbus RTU (Remote Terminal Unit) is designed tocommunicate with any controller that supports theinterfaces defined in this document. It is assumed that thereader has full knowledge of the capabilities andlimitations of the controller.7.6.3 Modbus RTU OverviewRegardless of the type of physical communicationnetworks, the Modbus RTU Overview describes the processa controller uses to request access to another device. Thisprocess includes how the Modbus RTU responds torequests from another device, and how errors are detectedand reported. It also establishes a common format for thelayout and contents of message fields.During communications over a Modbus RTU network, theprotocol determines:• How each controller learns its device address• Recognises a message addressed to it• Determines which actions to take• Extracts any data or other information containedin the messageIf a reply is required, the controller constructs the replymessage and sends it.Controllers communicate using a master-followertechnique in which only one device (the master) caninitiate transactions (called queries). The other devices(slaves) respond by supplying the requested data to themaster, or by responding to the the query.The master can address individual slaves, or can initiate abroadcast message to all slaves. Slaves return a message,called a response, to queries that are addressed to themindividually. No responses are returned to broadcastRS-485 Installation and Set... Design Guide154 Danfoss A/S © Rev. 06/2014 All rights reserved. MG20Z20277