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So like the subject line states...

Need to get sensor data from an Arduino Pro Mini to a Arduino Mega that is about 150 feet away from each other (maybe slightly less) both operating at 5VDC.

Do I need to convert to RS485? I could use XBEE radios but that adds a few more components to go wrong. Plus the radios would be at least 25.00 each. Basically I am using the Milone eTape sensors to go to a controller to control a well pump but the lake and the well pump are about 100-150 feet from each other. To top it all off the "installers" did not bury a conduit when they just replaced the 4" pipe so they put an inline connector on both sides so we can float the wire through the water line. All fun stuff. Maybe the radios would be the better solution? Any guidance, help suggestions would be greatly appreciated here.

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  • \$\begingroup\$ You can also send/receive your data using bluetooth HC05 \$\endgroup\$
    – Aircraft
    Commented Nov 21, 2015 at 10:35
  • \$\begingroup\$ Bi-directional data? What RF ISM bands can you use in your country? Have you checked prices of submersible cable? \$\endgroup\$
    – Andy aka
    Commented Nov 21, 2015 at 11:34

2 Answers 2

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Because cost was mentioned I'd consider the NRF24L01 based 2.4GHz modules. You can pick them up for pennies and some have reported over 100m range using external antennas so they may be adequate if you have relative line of sight.

They may or may not meet your requirements for link reliability, but like you said, it's all fun stuff and I've found these modules to be very fun to experiment with.

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  • \$\begingroup\$ If I decide to go the radio route I would stick with something like an XBEE for the 25.00 price. \$\endgroup\$
    – tekati
    Commented Nov 22, 2015 at 1:41
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150 feet, is pushing it for RS232, it'll probably work if you choose the right wire and a slow signal rate, 5V signaling on the bare UART pins is unlikely to work well at that distance. RS485 or some other balanced scheme like MIDI is pretty much required for that sort of distance.

radios may not work well during an electrical storm, wired connections may not work at all after an electrical storm.

is power-line signalling an option?

Putting wire inside the water pipe is asking for trouble, any turbulence in there will soon break it.

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  • \$\begingroup\$ I really did not think about turbulence in the pipe causing the wire to break so that is a valid concern. They make a special pipe fitting to do exactly what they did so it must be a doable solution with the right wiring. But you did answer my questions on the cable length. I was weary of RS232 and was pretty darn sure that 5V low voltage would not cut it so it sounds like its a radio or RS485. \$\endgroup\$
    – tekati
    Commented Nov 22, 2015 at 1:43

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