For another project (my digital bee hive) I'm planning on communicating with several arduinos to collect their sensor data. I plan on using RS-485. Here is the circuit that I plan on using. The circuit needs to be as robust as possible, thus the isolation from the AVR, but I'm not sure what isolation (diodes, or whatever) that there should be from node-to-node on the RS-485 network... anyone familiar with this, or anyone know of some rock solid industrial designs for RS-485?
Any help would be appreciated in getting this circuit as correct as possible, thanks!
If you are sure you need isolation, a quick search turned up the [u]LTC1535[/u]. Since RS-485 is differential, it has fairly good noise immunity and you may not need isolation.
...but I'm not sure what isolation (diodes, or whatever)
There are 3 isolation methods - Optical, electromagnetic (transformers), and mechanical (relays). Optical is usually the best & cheapest. Transformers have a limited bandwidth (i.e. They don't work at all with DC). Relays only work with DC.
Yea that short to ground was my mistake I make a lot of those.. heh
Here's a revised schematic, still haven't decided on the pinout to the RJ-45 jack yet, there apparently is no "standard".... so ground isn't connected, not shure where to put those yet.
The B to Y and A to Z links with a 50pF protection caps are from the example circuit on page 8 of the datasheet. It doesn't say exactly if A = Z or A = Y but by the way the connect A to Z I'm assuming A = Z... sigh
I separated everything out in the datasheet so it's more modular and understandable by me. When I start connecting multiple chips and circuits together wires start going a bit nuts.
I make a lot of those.. heh