In a short while I’ll need to look into making a data logger with wireless data retrieved. The Zigbee modules look like they will fit the bill, but I would like to know if the modules are all completable, i.e., if I buy a couple of XBee 1mW ones for developing the product, could I then simply swap these for the two XBee pro 900 for the extra range? Would the XTend 900 1W also be interchangeable?
The data loggers will be on an oil platform (possibly North sea) and we need to either retrieve the data from the shore (about 4 mile away), or from a boat close to the rig.
just FYI:
XBee’s are based on the IEEE 802.15.4 standard, a cousin of 802.11 (WiFi).
ZigBee ™ is not IEEE nor is it a synonym for 802.15.4.
It is a licensed mesh routing protocol from the ZigBee Alliance, used when meshing is needed.
XBee Series 2 are ZigBee (only).
XBee Series 1 are non-ZigBee, and are popular for non-mesh networks, or point to point.
Series 1 and Series two use 802.15.4.
If you choose the 2.4GHz XBee modules, you may achieve, in clear line of sight, with simple antennas, about 1/3 mile range with the 60Mw XBee Pro, and about 200 ft. with the 1mW (non-PRO). Range is far greater with high gain antennas in both cases. The line of sight range is very easily calculated, given some choice of antennas.
The modules with the similar package, for the North American ( legal) 902-928MHz band (unlicensed), are similar, but the lower frequency of course has less path loss. But offsetting that is that at 900MHz, it is awkward to get high antenna gain. So the disadvantage of 2.4GHz can be almost offset with antenna gain, in line of sight.
Both have “transparent” serial port extension which might be enough for your application. Depends!
Star topology ?
Thanks, you have been very helpful. I probably can’t use the 900 band here in the UK (GSM?) so its going to have to be the 2.4.
I think I’d best go for the 50mW from the start, my development monitoring location (my field) is about 500m from my office, in a line of site, but with some hedges and the odd tree.
ecotack:
Thanks, you have been very helpful. I probably can’t use the 900 band here in the UK (GSM?) so its going to have to be the 2.4.
I think I’d best go for the 50mW from the start, my development monitoring location (my field) is about 500m from my office, in a line of site, but with some hedges and the odd tree.
Not sure, but I believe, like in the EU, the UK can use 868MHz, and there are a few 802.15.4 products for that band.
http://www.digi.com/products/wireless/p … p#overview
Note that the 868 MHz version is harder to obtain, Digi won’t sell to individuals and all the online stores that carry them (that we found) had insane markups (+80%). Order through your employer directly from Digi, if you can. That worked for us.
hobby/student apps rarely need meshing.