The Series 930s/935s Transmitter /Controller can operate as a relay controller with user controlled setpoints, as 4-20 mA gas transmitter and it can communicate via RS485 on a network. PC Networking & Data logging Software for connecting the RS485 network of S930s/S935s monitors to a computer is available as an option. Please contact your distributor if you require this. The S930s/S935s monitors can be supplied with or without a LED display. If you have ordered a monitor with display the 4-20 mA loop will need to be powered in order for the display to function correctly. If the loop is not powered then the display will typically display -.125.