What is the maximum Ethernet cable length?

The maximum Ethernet cable runs for the Hardy controllers which includes:

the HI 3000 series (which include the HI 3010 & HI 3030); 
the HI 4000 series (which includes the HI 4050 & HI 4060);
the HI 6000 series (which include the HI 6300/6310, HI 6500/6510, & HI 6600);

is 100 meters (328 feet). Any distance of more than 100 meters require a hub or electronic amplifier/relay to boost the signal. The longer the cable, the slower the communications rate.

Consult your IT department for recommendations on signal boosters and hub equipment.