Modbus RTU over XBee network??

[Some Anon Guy]

I have the need to make a serial RS232 Modbus board wireless.
I was thinking of using XBee wireless modules.

Anyone ever done this with Modbus/RTU?

How did it work?

Also, in theory, this should allow me to then have multiple of these boards on the wireless network (The PLC does allow me to identify my ID# which serial device to communicate with)...
RS232 is a point to point, and if I can convert to XBee wireless, and get more boards on the same network, that would be great...

I have never built wireless into my designs, so please forgive any naivety... I am learning...

[xeontory]

You can directly implement Modbus RTU with Xbee modules in 2.4GHz, 900MHz, 868Mhz. Higher frequencies are more directive in nature and requires line of site operation to minimize packet loss.

I guess you will implement this in an industrial environment. If so, you should be concerned about the mesh network design : to configure appropriate number of routers, coordinator devices and the end devices. Consider their positioning on site with possible fixed and movable obstacles, canopies etc. Consider every building as Faraday Cage : http://www.thedailysheeple.com/wp-content/uploads/2014/08/faraday-cage.jpg

Is powering the nodes is an issue? If it is then you should calculate which units will have more radio traffic and ensure more power for them.

If you consider XBee-PRO 2.4GHz embedded RF modules from Digi International, then meshing will be automatically establish by their propitiatory DigiMesh protocol. Read more : http://www.digi.com/pdf/wp_zigbeevsdigimesh.pdf

Zigbee is one of the wonderful protocols to work with. As you are designing the product yourself, instead of using modules you can also implement it as a stack.