Which Xbee to buy

Hello!

I have a question about xbee modules... I need a reliable wireless communication (UART) between two arduinos. I never had an xbee module, so i don't have any experience with them.

Does anyone know

  • how stable is the connection between a fixed point to point network
  • how fast do they connect with each other
  • do they always reconnect if one of them has a power loss?

Thank you!

Hi Tady.
With wireless, the answer unfortunately is always "it depends". Let's go through your questions one by one.

Q1) how stable is the connection between a fixed point to point network 
Q2) how fast do they connect with each other 
Q3)  do they always reconnect if one of them has a power loss?

A1) The stability actually depends on the data rate and the range that you need to operate over. Truthfully, there are a bunch of other things that would affect the connection reliability too, but those would be the main ones. For a fairly close connection, and perhaps data rate similar to an average person typing, it would probably be fine.

A2) You have to pair the two modules if you want to use the transparent UART mode but as far as I know, as soon as you turn them on, they should be ready to go (give or take a couple of milliseconds).

A3) This is a bit less clear. It's possible they would reconnect, but the problem would be if one module goes down and the other module doesn't know. The module that went down would have to rejoin the other module, but its uncertain how it would handle a second join. It might be fine by presenting the same address and PAN ID or it might get rejected. You'd have to try and find out.

Hope that helps.