notifier

[Фарах]

Hello!

i am new to labview

i want to know if it is possible to implement the architecture of master-slave for a rs-485 protocol using notifiers ?

thanks

[GerdW]

Hi Faraah,

implement the architecture of master-slave for a rs-485 protocol using notifiers ?

How many notifiers do you want to use? And which data should they contain?

What is the master and what is the slave in this "rs485 protocol"?

And how is all that related (master-slave architecture, RS485, notifier)?

[Фарах]

i have microcontrollers (atmega) and i want to exchange data between these microcontrollers and i want to design an interface that match with description above.

master will send a message contains the address of slaves (slave- which process data from sensor connected with it) then slave will send back these data to master and data from slave will be displayed.

i didn't find any idea that help me , but i read about notifiers there is a master-slave architecture .. but i don't know if i can use this architecture to work with serial communication

[GovBob]

RS-485 only specifies electrical characteristics of the generator and the receiver: the physical layer. It does not specify or recommend any communications protocol.

RS-485 is used as the physical layer underlying many standard and proprietary automation protocols used to implement Industrial Control Systems, including the most common versions of Modbus and Profibus

Straight off of wikipedia.

[deceased · Accepted solution]

I think this may be one of the cases where the same terminology is used for different things in different fields, leading to confusion.

With many RS485 networks I have seen, master slave is used to dictate how the nodes communicate. It usually just means that the nodes cannot "talk amongst themselves", they are only allowed to respond to their master, when it explicitly asks that device a question. 

The master slave pattern in LabVIEW is not this.

In LabVIEW, RS485 is just serial (likewise on the atmega, its just connected to a UART)

Do you intend to use full or half duplex RS485?

If half duplex you need to watch the line "turn around times" on the atmega side. Most USB->RS485 converters will deal with the PC end for you. I have used the FTDI ones in many projects and highly recommend them. 

For the microcontroller end, I have used MAX489 or DS3695 as the line transceivers in the past without issue.

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