Danfoss vlt aqua Design Manual

Also see for vlt aqua: Instructions Instruction manual Operating instructions Design guide Operating instructions

Contents

Danfoss vlt aqua Design Manual Manual pdf 187 page image

7 RS-485 Installation and Set-up7.1 RS-485 Installation and Set-up7.1.1 OverviewRS-485 is a two-wire bus interface compatible with multi-drop network topology, i.e., nodes can be connected as a bus, or via drop cables from a commontrunk line. A total of 32 nodes can be connected to one network segment.Network segments are divided up by repeaters. Please note that each repeater functions as a node within the segment in which it is installed. Each nodeconnected within a given network must have a unique node address across all segments.Terminate each segment at both ends using either the termination switch (S801) of the adjustable frequency drives or a biased termination resistornetwork. Always use shielded twisted pair (STP) cable for bus cabling, and always follow good common installation practice.Low-impedance ground connection of the shield at every node is very important, also at high frequencies. This can be achieved by connecting a largesurface of the shield to ground, by means of a cable clamp or a conductive cable gland, for example. It may be necessary to apply potential-equalizingcables to maintain the same ground potential throughout the network, particularly in installations where there are long lengths of cable.To prevent impedance mismatch, always use the same type of cable throughout the entire network. When connecting a motor to the adjustable frequencydrive, always use shielded motor cable.Cable: Shielded twisted pair (STP)Impedance: 120 OhmCable length: Max. 3,396 ft [1,200 m] (including drop lines)Max. 1,640 ft [500 m] station-to-stationVLT® AQUA Drive Design Guide 7 RS-485 Installation and Set-upMG.20.N5.22 - VLT® is a registered Danfoss trademark 7-17