RS485 communication OSI model network layer

Network layer processing occurs in RS485 On the bus Actual communication between devices . because RS485 The interface is mainly an electrical specification , So the conversation can end here , But because it supports more , So you need to  OSI  Solve it in the model .

There is no fixed specification for network layer addressing , but RS485 The bus must be properly managed by the host to avoid bus conflicts . When multiple devices try to communicate at the same time, a bus conflict occurs , This is very harmful to the network . When there is a conflict , The transmitter conflicts at both ends and effectively generates a short circuit . This will cause each device to consume a large amount of current , Thus, the transceiver enters the thermal off state .

To avoid communication conflicts , The host controls the bus and invokes various devices . This is usually achieved by having a command set that only a specific device can recognize or by having a specific address for each device . Because the bus is shared among all devices , Therefore, every device will see the command sent by the master device / Address , But only when the single device is asserted will it respond .

chart 11： Defines the  OSI  Model