Standard RF circuits are also out of the question as they would be interfered by the large 200hp motors and the large collection of other noisy goods. (both physically and RF)
Connecting the Rx and Tx pins together is not an option as the area this will have to cover is a rectangle of about 1000yd by 300yd
Oh and btw my dad also wants the data to be live on the spreadsheet.
And just out of curiosity, what is the record of the most arduinos connected into a network like the one I'm planing on?
I'm planning a project that will do 254 Arduinos over (theoretically) 300km
Some fairly inexpensive radio transceivers ( RFM22B or the SIM20 433 MHz, or the 2.4 GHz RFD21733 ) can be connected as a mesh with multiroutes, aknowledge, and autoresend.I get 500m from the SIM20 outdoors, but it might be better using the 2.4 GHz does WiFi work OK in the factory ? its basically the same frequency.
What is the spreadsheet for? I mean, what calculations is it performing and what is being done with the results?Although you've specified that the results must be displayed in a spreadsheet, use of a spreadsheet is a solution not a requirement; the fact you're also asking for 'live' updates make me suspect the spreadsheet is not actually suitable for you. What is the actual requirement here?Do you want a tabular display of the counters in some order? Over some period? Any of that user-defined? Charts of the rate of change or absolute values over time? The real requirements will imply the most appropriate way to store and present the data, and it may not be a spreadsheet.
Seriously though, has anyone modulated laser pointers? and what range is possible? Of course there would be environmental interference from rain and mist, but I have a specific project I want to test sometime.
A standard RF circuit will not work in the environment I plan to implement. Have you seen the inside of your standard cereal factory? Think of all the motors that drive the lines and multiply their HP by around 30-600 and you get what I'm working in. The factory manufactures puzzles so we have a large amount of motors and controls running an this will be the first arduino ever present in the factory. Almost all the systems there are industrial-grade PLC's from Allem Bradley or Mitsubishi.
Say what? What have you actually done to measure the RF noise in the factory? Most industrial motors are probably three phase squirrel cage induction types that may not produce much RF issues. What does the HP rating of a motor have to do with its potential RF production?