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Communication - Modicon M340 Plc Page 2-38



Modicon M340 Magelis XBT Preventa XPSMC Altivar 71 Twido Lexium 32 LU9GC3 Modbus

Third-party Modbus device

The Modbus serial link is used for master/slave architectures (it is necessary, however, to check that the Modbus services used by the application have been implemented on all relevant devices). The bus consists of a master station and slave stations. Only the master station can initiate the exchange (direct communication between slave stations is not possible). Two exchange mechanisms are available: b Question/response, where requests from the master are addressed to a given slave. The master then waits for the response from the slave which has been interrogated. b Broadcasting, where the master broadcasts a message to all slave stations on the bus. The latter execute the order without transmitting a reply. The Modicon M340 platform offers serial link connection options for Modbus or Character mode: b Via the serial link integrated in the following processors: v Standard processor BMXP341000 v Performance processors BMXP342000 / 20102 / 2020 / 20102CL The number of serial link modules is limited by the maximum number of application- specific channels permitted per station, depending on the type of processor: b Standard processor BMXP341000 : maximum of 20 application-specific channels (1). b Performance processors BMXP342 pppp : maximum of 36 application-specific channels (1).


Processors with integrated serial link BMXP341000 / 2000 / 20102 / 2020 / 20102CL processors integrate a serial link which can be used with either the Modbus RTU/ASCII master/slave protocol or with the Character mode protocol. These processors have the following elements on the front panel, relating to the serial port: 1 A display block including at least the following LEDs: v SER COM LED (yellow): Activity on the serial link (lit) or fault on a device present on the serial link (flashing). 2 An RJ45 connector for Modbus serial link or Character mode link (non-isolated RS 232C/RS 485) with its black indicator (2) .

Note: For more information about the processors, see page 1/11 (1) Application-specific channels: BMXEHC0200 counter modules (2 channels), BMXEHC0800 (8 channels), BMXMSP0200 motion control modules (2 channels) and BMXNOR0200H RTU communication module (1 channel). (2) For isolated serial links, the TWDXCAISO isolation box must be used.

Modicon M340 automation platform

Modbus and Character mode serial link

Presentation, description

Processors: page 1/8 Ruggedized Modicon M340 modules: page 3/2 BMXP3420102/20102CL BMXP341000/2000/2020

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