BTC1800 is a microprocessor-based controller with universal input, analogoutput, and up to 4 relays (control or alarm) that may be controlled through a number of algorithms such as ON/OFF, ON/OFF heating/cooling duplex, motor-valve control, PID, and self-tuning PID. A bumpless auto-manual change-over is built in the PID algorithm. A start-on timer allows one of output relays to be time-controlled. Two displays (for the measured value and for the set point) as well as an output-control bargraph ease operator duties. Carefully protected from electromagnetic disturbances by featuring both input and output optical isolation, BTC1800 is well equipped for trouble free operation in harsh industrial conditions. and PID-autotune control algorithm.