artemis global tracker - adding rs485 modbus RTU capability - and/or measuring analog signals

Is it practical to think in terms of adding modbus RTU over RS485 to Artemis Global Tracker ?

Is it possible to use Arduino.cc MKR shields with AGT ?

I’m getting conflicting advice on whether the Artemis on the AGT could be used for all of the IoT processing

Some are saying it can easily handle the external IO, while others are saying

an external Nano could process the IO and/or modbus RTU vis rs485 comms and pass data to the Artemis

Ideally the resultant system would have the capability of:

2 or 3 analog IN

2 or 3 Digital IN

1 (high speed) Digital counter input for measuring period / frequency

1 or 2 Digital OUT

If not too hard: RS485 for retrieving device data via Modbus RTU

If the AGT WRL-18712 can handle a chunk of that and maybe use a Uno or Nano for additional IO

Could the AGT use an Arduino.cc MKR rs485 shield ?

I assume that the native serial channels are already busy with GPS and Sat

Please see: https://forum.sparkfun.com/viewtopic.ph … 35#p239535