horace:
how far apart are the data loggers? how much data and how fast do you need to transfer it?
consider RS485, Ethernet, Wifi, etc
The data logger will be near, max 1 meter at the meddle of the network and the role network will be, max 3 ~ 4 meters end to end.
About speed, I still had not thought about it...
The volume of data is small for each call. Thinking text file, around 10 lines whit max 100 character.
I was thinking (studding) I2C, RS485 and ISP.
Thanks