The Nova PD540 is a digital temperature controller with auto-tuning PID capabilities that is available in 1/16, 3/16, 1/8, and 1/4 DIN sizes. Models include standard one-directional control (i.e. heating or cooling) or bi-directional heating and cooling control. One of four user programmable set points may be selected for PID control in the form of time proportional relay on/off output, time proportional voltage pulse output, or 4-20 mA signal control. Its universal input accepts 23 input varieties, including thermocouple, RTD, and voltage inputs, and it can be easily configured for a 4-20 mA input. It is available with up to three (3) relays, two (2) 4-20 mA analog outputs, two (2) digital inputs, and an RS485 serial communication option which includes protocols for master/slave set point control, Modbus® ASCII and RTU, as well as PC software.