Galil Motion Control RIO-47 series RIO-47100 User Manual

Galil Motion Control RIO-47 series
RIO-47100 User Manual Manual pdf 23 page image

ModbusAn additional protocol layer is available for speaking to I/O devices. Modbus is an RS-485 protocolthat packages information in binary packets that are sent as part of a TCP/IP packet.Modbus/TCP requires an Ethernet connection between master and slave. Modbus/TCP also requiresthat all slaves communicate with their masters over port 502. See the IH command to setup portcommunication for the RIO.The Modbus protocol has a set of commands called function codes. As a Modbus Class 1 device, theRIO-47xxx supports the 10 major function codes:Function Code Modbus Description1 Read Coil Status2 Read Input Status3 Read Holding Registers4 Read Input Registers5 Force Single Coil6 Preset Single Register7 Read Exception Status15 Force Multiple Coils16 Preset Multiple RegistersTable 3.2: Supported Modbus function codes and descriptions.All modbus function codes listed in Table 3.2 are supported by the RIO when it operates as a master(client) or when it operates as a slave (server).Note: The remainder of this chapter uses the '$' symbol to signify that numbers are in hexadecimalnotation.As a Modbus MasterThe RIO-47xxx provides three method of Modbus communication as a master:1. The first method of Modbus communication uses standard Galil commands. The followingcommands support Modbus:@IN[], @AN[], @OUT[], SB, CB, OB, and AOSee the RIO command reference individually for each command on how to address a Modbusslave.2. The second method uses the MB command that requires the user to enter a select a few keyparameters and allows the controller to build the Modbus packet. The formats vary dependingon the function code that is called. For more information refer to the MB command in CommandReference3. The final method allows the user to send raw Modbus packets. This gives the user completecontrol over the creation of their Modbus packet including transaction identifiers, protocolidentifiers, length field, Modbus function code, and data specific to that function code.. To send araw Modbus packet the user must set the MB command with a function code of –1. For moreinformation refer to the MB command in Command ReferenceThe following sections provide a full description of each method.Chapter 3 Communication ▫ 23 RIO-47xxx Rev 1.0r