4-20mA and zigBEE

[TMI]

Hi,
As there is a lot of choices with RevPi modules I don't know what to take now.

I need to generate 4-20mA signals for another automate and to communicate with a zigBee module.
Do those modules exists ?
I know I can plug a USB converter to have zigBee communication but the antenna could be removed by accident which can't be tolerated for my application.

If not I would like to create my own module and I wondered if tutorials exist about that before developping on RevPi.

Thank you in advance

[dirk]

Dear TMI, could you describe your target application and an give an estimation about the amount of modules you want to order per year?