ABB REPL-01 User Manual

Contents

Communication41CommunicationWhat this chapter containsThis chapter describes the communication on an EthernetPOWERLINK network.Ethernet POWERLINK communication cycleIn an Ethernet POWERLINK network, one of the nodes, forexample a PLC, motion controller or industrial PC, is designatedto function as the Managing Node (MN), the master in thenetwork. All other devices operate as Controlled Nodes (CN),slaves in the network. The MN defines the clock pulse for thesynchronization of all devices and manages the datacommunication cycle. In the course of one clock cycle withinwhich all nodes are addressed, the MN sends Poll Requests(PReq) to all CNs one after another. They reply immediately to theprompts with Poll Responses (PRes).An Ethernet POWERLINK cycle consists of three phases. Duringthe start phase, the MN sends a Start of Cycle Frame (SoC) signalto all CNs to synchronize the devices. Payload data exchangethen proceeds in the second phase, the isochronous phase. Thethird phase, the asynchronous phase, allows the transfer of largepackets that are not time-critical, for example parametrizationdata.PReqCN2AsynchronousphaseIsochronousphasePReqCN1PResCN1PResCN2SoC PReqCNnPResCNnSoAAsyncdataMNCNEthernet POWERLINK communication cycleStartphasePhone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com