Re: [bascom] RS485

[MWoeste@t-online.de (Michael Woeste)]

Hi all,

maybe it is much better to use a CAN-BUS for these purposes. The complete
protocol and arbitration is done by a cheap CAN-BUS chip, and the resources
on the embedded cpu are free for other purposes.
CAN-BUS is much faster than RS485 and can be up to 1 kilometer length. With
only 100 m, you will get 500 kBit/s. CAN-BUS is two-wire bus with
termination resistors at both ends..

If you are interested, look at elektor / elektuur september and october
issue. CAN-BUS
offers much more advantages than I can tell here.

best regards
Michael



> Hi all,
>
> For my project I will have about 10 modules interconnected by rs485.
> Total cable length less than 100 metres and the baudrate 115K2.
> Each module will have its own address.
> 3 modules will have a display and a keypad and must be able to quickly
> retrieve actual data from the 7 modules.
> This could be done on-demand or whenever the data of one of the modules
> changes.
> For the communication I will use the 9-bit format where the 9th bit will
> determine whether the byte represents an address or data.
> The packet length will be 64 bytes at most and the overall traffic on the
> network will be light.
>
> I've been reading Jan Axelson's book "Serial port complete" but I do not
> want to use a master/slave or token-passing protocol and she says that the
> collision detecting protocol is not suitable for rs485 ?!
>
> I'm hereby seeking for general advise, dos and donts.
> A possibility to upload the program over rs485 would be fantastic.
>
> Thanks,
>
> Eric Le Baron
> Wageningen
> The Netherlands
>