Danfoss VLT 8000 AQUA series Operating Instructions Manual

Also see for VLT 8000 AQUA series: Instruction manual Operating instructions

Contents

Danfoss VLT 8000 AQUA series Operating Instructions Manual Manual pdf 149 page image

VLT ® 8000 AQUAProgramming■ Serial communication for FC protocol■ ProtocolsAs standard, all VLT 8000 AQUA units have a RS 485port which enables a choice among four protocols.• FC• Profibus*• Modbus RTU*• DeviceNet*• LonWorks** Please note that these are option cards withseparate input terminals.■ Telegram communicationControl and reply telegramsThe telegram communication in a master/slave systemis controlled by the master. A maximum of 31 slavescan be connected to one master, unless a repeateris used. If a repeater is used, a maximum of 126slaves can be connected to one master.The master continuously sends telegrams addressedto the slaves and awaits reply telegrams from these.The response time of the slaves is max. 50 ms.Only a slave that has received a faultlesstelegram addressed to that slave will responseby sending a reply telegram.BroadcastA master can send the same telegram at the sametime to all slaves connected to the bus. In suchbroadcast communication, the slave does not senda reply telegram to the master, provided the telegramhas been correctly received. Broadcast communicationis set up in the address format (ADR), see the nextpage. Contents of a character (byte)Each transferred character begins with a startbit. Subsequently, 8 data-bits are transferred,corresponding to one byte. Each character is securedvia a parity bit set to "1" when there is even parity (i.e.an even number of binary 1’s in the 8 data-bits andthe parity bit combined). A character ends with a stopbite and thus consists of a total of 11 bits.■ Telegram build-up under FC protocolEach telegram begins with a start character (STX) =02 Hex, followed by a byte that gives the telegramlength (LGE) and a byte that gives the VLT address(ADR). Then follows a number of data bytes (variable,depending on telegram type). The telegram endswith a data control byte (BCC).Telegram timesThe speed of communication between a masterand a slave depends on the baud rate. Thebaud rate of the frequency converter must bethe same as the baud rate of the master and isselected in parameter 502 Baudrate.After a reply telegram from the slave, there must bea minimum pause of 2 characters (22 bits) beforethe master is able to send another telegram. At abaudrate of 9600 kbaud, there must be a minimumpause of 2.3 msec. After the master has completedthe telegram, the response time of the slave backto the master will be max. 20 msec. and there willbe a minimum pause of 2 characters.MG.83.A2.02 - VLT is a registered Danfoss trademark 149