If you have ever needed to make an RS-232 over a longer distance this is what you needed.  No need to run wires.  Just set up this and go.  It uses wireless to accomplish the same thing.  Transmit power is 200 mWatt so range is not a problem.  Up to 500 feet (152 m) indoors; Up to 3 miles (5 km) line-of-sight

Qty=3 in the package type of the first image

Qty=1 in the package type of the second package

Both are the same unit. Just different package.  Requires DC power anywhere in the range of 7 to 15 volts.

These cost about 175 EACH which you can see in the MOUSER CATALOG

The first pdf file is the manual hardware manual for the part number that the manufacturer steers you to when you search on CL5124

The second pdf file is the software setup guide.

Manufacturers website here: http://www.aerocomm.com