RS 485 and microcontroller

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movie_freak

Joined: 20 Mar 2007
Posts: 81
Helped: 2

31 Oct 2009 6:47 RS 485 and microcontroller

Hi,

I want to interface RS 485 with a microcontroller, its ok with the hardware part, I am going to use a ISO3088 isolated 485 chip from TI. I'll connect one of my uart to its input from the controller which would be master...... now from its output i want to connect some slaves. I know that max slaves possible = 32 and would also depend on the communication cable length. I want help regarding the software side logic.

My requirement is Full duplex but it should be able to send data from master whenever needed and slave will only reply when master queries them.

I am thinking to implement in this way:
I'll make packets with header and payload(data). The header would contain information about the data like slave address, checksum, whether it is data to be accepted or it is a query command

I wanna know is this way of doing it is correct? or there is any better way?

Many Thanks,
Regards,
Surya

bobcat1

Joined: 10 Jul 2002
Posts: 1118
Helped: 48

31 Oct 2009 14:57 Re: RS 485 and microcontroller

HI

you need to configure you network in star configuration - 1 master and many slaves

You don't need full duplex communication if the slave is only going to answer when master allow him to do so

Protocol is need needed in star configuration

All the best

Bobi

The microcontroller specialist