hi all,
I am planning to build a long wire master slave communcation system with less no: of wires . that i need around 2 km distance with many slave systems ( < 128). my question is which protocol is best suited for this system and welcomes design ideas ,circuits etc
Hello
TI company have SN65HVD22D and similars for RS485 communication for long distances and noisy environment,you can use RS485 repeaters for more distances if you want.
You can MODBUS protocol for master slave operation,see w*w.m*odbus.org
If u have single master and slave (point to point) then you can use zarlink ST-BUS and MT9172 IC,it is suitable for 5km cables with 1 bit error in millions at this lenght.
I have tested RS485 with vulgaris 75176 at 4.2 Km @ 9600 bps and 2 slaves, the wire was 0.7mm telephone cable.
I don't understand the question of protocol, the distance is un electrical factor, you can use what you want, i use my protocol with 16bit crc, so i can make all that i think