Tuning of PID DDC controllers

When a system changes from pneumatic control to direct digital control (DDC), installers and site engineers lose the analog gages and logic they previously used to monitor the system. They also find it more difficult to tune DDC control algorithms properly and tend to set operating variables at less-than-optimum values, thus negating the benefits of controller technology. To maximize utilization of advanced controller equipment, field engineers must have proper initial values for the gains in proportional-integral-derivative (PID) calculations, and they must have adequate tools to monitor the effects of PID operation and adjust gains as needed.