1766-RM001A-EN-P MicroLogix 1400 Programmable Controllers ...

Chapter 23Socket Interface Using CIP Generic MessagingOverviewThe socket interface allows you use a MicroLogix controller tocommunicate, via the Ethernet Subsystem, with Ethernet devices that donot support the EtherNet/IP application protocol, such as bar codescanners, RFID readers, or other standard Ethernet devices.Before you use the socket interface, you should be familiar with thefollowing:• basic TCP/IP, UDP, and socket programming concepts.• how to write socket programs in a programming language, such asC or Visual Basic.• how to use diagnostic tools, such as a network sniffer.• the application protocols of the devices and applications with whichthe MicroLogix controller will communicate.• how to write ladder logic for a MicroLogix controller.Socket InterfaceArchitectureThe socket interface is implemented via the Socket Object in the EthernetSubsystem. MicroLogix controller programs communicate with the SocketObject via MSG instructions. MSG requests to the Socket Object are similarto socket API calls in most computer operating systems. The SocketObject services let you open connections, accept incoming connections,send data, and receive data.To communicate with another device, you must understand the otherdevice's application protocol. The Ethernet Subsystem has no applicationprotocol knowledge — it simply makes the socket services available toprograms in MicroLogix controllers.Number and Type of SocketsYou can create as many as 8 socket instances. Each socket instance can beone of these socket types:• UDP socket (to send/receive UDP datagrams)• TCP client socket (RSLogix500 initiates the connection)• TCP server socket (another device initiates the connection toRSLogix500)479 Publication 1766-RM001A-EN-P - October 2008