Installation guide

ManualsBrandsWeidmuller ManualsComputer equipmentSL-MOD-GW

4 PV Clinics Installation Manual 21/07/11 01.00 01/12

4. Surge protection ................................................................................................. 14

4.1 Best practice for PV Plants ............................................................................................................ 14

4.2 Common mode and differential voltages...................................................................................... 14

4.3 Types of surge protection devices ................................................................................................ 15

4.3.1 DC arresters for PV Array side protection ......................................................................... 15

4.3.2 AC arresters for supply side protection .............................................................................. 15

4.3.3 Surge protection for data communications equipment ...................................................... 15

5. Data Communications ........................................................................................ 16

5.1 General ............................................................................................................................................. 16

5.2 RS485 signals .................................................................................................................................. 16

5.2.1 Two wire RS485 ................................................................................................................. 17

5.2.2 Cable Shields ..................................................................................................................... 18

5.2.3 Mixed devices on Transclinics networks ............................................................................ 18

5.2.4 Data Cables ....................................................................................................................... 19

5.2.5 Network Topography.......................................................................................................... 19

5.2.6 Termination resistances ..................................................................................................... 20

5.2.7 Addresses, network length and repeaters ......................................................................... 20

5.3 Rules for reliable RS485 networks ................................................................................................ 21

6. Modbus ................................................................................................................ 22

6.1 General ............................................................................................................................................. 22

6.2 Modbus RTU .................................................................................................................................... 22

6.3 Alternative communications methods .......................................................................................... 23

6.3.1 Modbus TCP (Ethernet) ..................................................................................................... 23

Copper Ethernet Links ................................................................................................................... 23

Fibre-optic Ethernet links ............................................................................................................... 23

6.4 Modbus Maps .................................................................................................................................. 24

6.4.1 Calibration values (Holding Register Values) – for reference only .................................... 24

6.5 Measurements (Input Register Values) ......................................................................................... 25

6.6 Register Values ............................................................................................................................... 26

6.6.1 Holding Register Values .................................................................................................... 26

6.6.2 Input Register Values......................................................................................................... 26