GE B30 Communications Manual

Also see for b30: Maintenance manual Instruction manual Instruction manual Instruction manual Instruction manual

Contents

UR FAMILY – COMMUNICATIONS GUIDE 2-1UR FamilyChapter 2: Modbus communicationModbus communicationThis chapter outlines the Modbus protocol, which is a standard protocol used for communication among devices. Use theModbus memory map provided when designing a client to access the UR device using Modbus.2.1 Modbus RTU protocol2.1.1 IntroductionThe UR family supports several communications protocols to allow connection to equipment such as personal computers,remote terminal units (RTUs), supervisory control and data acquisition (SCADA) masters, and programmable logiccontrollers. The Modicon Modbus protocol is the most basic protocol supported by the UR. Modbus RTU is available via theRS232, RS485, or USB link (for graphical front panel), and Modbus TCP/IP is available over Ethernet. The followingdescription is intended primarily for users who want to develop their own master communication drivers. Note that:• The UR always acts as a slave device, meaning that it never initiates communications. It listens and responds torequests issued by a master computer.• A subset of Modbus RTU and Modbus TCP/IP protocol format is supported that allows extensive monitoring,programming, and control functions using read and write register commands.2.1.2 ConfigurationThe Modbus slave address and TCP port number are configured during installation. See the Modbus Protocol section in theSettings chapter of the Instruction Manual.The number of remaining Modbus TCP connections available can be viewed in the Actual Values > Status > Comm StatusRemaining Connect option. The value is 4 when the EnerVista software is closed. See the Remaining Connection Statussection in the Actual Values chapter of the Instruction Manual.2.1.3 Physical layerThe Modbus RTU protocol is hardware-independent so that the physical layer can be any of a variety of standard hardwareconfigurations including RS232, RS485, and USB (for graphical front panel). The relay includes a front panel RS232 port anda rear terminal RS485 port. Data flow is half-duplex in all configurations. See chapter 3 of the Instruction Manual forcommunications wiring.