Communication networks

Layer 1: physical layer This layer is defined by the addressing, the path or the performancesof the system. The physical layer is the protocol’s elementary layer. It defines thetransmission mode, the medium (cable, etc.) and the network topology. Layer 1 (RS 232, RS 485) is defined by IUT Standards (International Union of Telecommunications). Layer 2: link layer Layer 3: networks This controls network access (e.g. master/slave system), the addres- sing control (emitter or receiver identity) and checking transmission errors. Layer 4: transport

Communication networks

(continued)

This layer provides point to point communication between the trans- mitter and the receiver and industrial monitors its quality. The standard solutions Layer 5: session

Protocols

The protocol must be chosen according to the application. Thedistance between the master and the slaves, the number of products on the link and the current network are so many parameters which will be considered when making the choice. Today there are several possible solutions: •For not very complex transmissions between different input andoutput units, protocols like Can or ASI can be used (example: link between products in the same range).• For transmissions between one or more supplier of actuators or detection withPCs or Plcs, protocols such as INTERBUS-S This controls flows and storage in the memory. Communication between several devices requires a common struc- ture and language: this is known as the protocol. Each type of link (JBUS/MODBUS, BATIBUS, EIBUS, etc.) has its own protocol defined by certain standards. However, all protocols are subdivided into 7 industrial levels called layers. Each layer receives elemen- tary information from the lower layer, processes it, and then supplies more elaborated information to the upper layer. DIRIS system uses layers 1, 2 and 7 only. Layer 6: presentation This layer provides the transcoding, the format, the conversion and the encoding. Layer 7: application layer The application layer consists of the highest information level and enables communication with the system user.
® , PROFIBUS
® orJBUS/MODBUS
® can be used.•For transmissions between PCs or between PCs and PLCs, indus-trialists are increasingly using the ETHERNET network with its TCP-IP protocol. In certain cases, by using specific interfaces, actuators are connected directly onto Ethernet from specific interfaces. Specific solutions There are also protocols that are specific to certain manufacturers. The latter generally propose gateways allowing the conversion of their protocol into a standard protocol of the JBUS/MODBUS
® type, forexample.
ManagementCentreMAP, ETHERNETFactory linkSupervisorsFIP ® , JBUS ® , PROFIBUS ® ® , INTERBUS-S ,…Checking andCommandoEIBUS ® , BATIBUS,JBUS/MODBUS ® ,… SensorsDIRIS catec_093_c_1_gb_cat. Fig. 1: example of industrial network

SOCOMEC general catalogue

This document is not a contract. SOCOMEC reserves the right to modify featureswithout prior notice in view of continued improvement. 2008 - 2009

D . 13