When distances longer than the 50 ft line length restrictions of an RS-232 connection is required. The short haul modem set can be used. The AX-969 Short Haul modem set can be used for connections of up to 7 miles in length. Using two twisted copper pairs of wire, a reliable data link between the two modems can be made.

Each modem includes transformer coupled links and opto-isolated RS-232 connections. Modem power is taken from the PC computer at one end and the data logger RS-232 port at the remote station. Typical minimum wire gauge between modems is 24 AWG with 22 and 19 AWG being most common. Central site short haul modem can be plugged directly into 25-pin RS-232 connection of the PC Computer.