To test out the networking operation on the unit, the previous sketch was modified to enable both local SD card writing and network broadcast of the data. This uses a modified version of the Ethernet web server example available with the Arduino software.
I was initially hoping to create a one “sketch fits all” solution as I believe the intention is to collect the data in the trial from several units possible running concurrently. Unfortunately it would appear that this will be a little more problematic than I had anticipated as each Arduino needs to be given its MAC address and IP manually. This could potentially be gotten around by using costly error catching or even random generation to prevent duplicate addresses.
However as each unit will be provided with an SD card, my currently preferred solution to will be to create a file for each unit storing the IP and MAC for that unit and have a standard sketch on all units that will read that info from the SD, removing the need for hard coding.