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

480 Socket Interface Using CIP Generic MessagingYou can partition the 8 available socket instances between UDP and TCPsockets by:• Using all 8 instances for client TCP connections.• Using all 8 instances to listen for incoming TCP connections andthen accept 8 connections from other device.• Performing both TCP client and server operations.• Performing both TCP and UDP operations.When you use the socket instance as a TCP server type, you don't need tomake a listen socket. Even if you would like to listen for incoming TCPconnections to the same port, you should create a new socket instance.No listen socket instance is supported.Available Socket ServicesSocket ServiceCreateSocketOpenConnectionAcceptConnectionReadWriteDeleteSocketDeleteAllSocketsSocket InstanceServer or ClientClientServerServer or ClientServer or ClientServer or ClientServer or ClientOnce you open a connection on a client socket instance, you cannot usethe same socket instance to accept incoming connections. Similarly, if youaccept connections on a socket instance, you cannot then use the instanceto open outgoing connections. This behavior is consistent with standardsocket API behavior.Typical Sequence of Transactions For a TCP ClientThe following diagram shows a typical sequence of socket interfacetransactions with the MicroLogix controller acting as a TCP client.Here, the MicroLogix controller sends data to a device and then thedevice sends a response. This is a typical sequence of transactions.Depending on the application protocol, the device could initiate sendingdata to the MicroLogix controller once the connection is open.Publication 1766-RM001A-EN-P - October 2008