Operating Instructions

Glossary
Glossary-4 Siemens Building Technologies, Inc.
PID
Proportional plus Integral plus Derivative gain. Functionality used in state-of-the-art control
systems to decrease the response time of the overall control process. The addition of the
derivative gain function to PI control results in the controller providing a control output signal
that is proportional to the rate by which the error is changing. Instead of the control output
merely being proportional to the error (as with proportional only type control), the magnitude
of the control output is significantly increased or decreased to reduce the time needed to
attain the desired setpoint.
PPCL
Powers Process Control Language. Programming language used to write control programs
for building control and energy management functions. PPCL consists of various types of
statements, each performing a different task. These statements become ordered instructions
called control programs that are executed at the field panel. These control programs instruct
the field panel on how to perform calculations, evaluate control strategies, performed time
based actions, and command points.
reheat coil
Hot water, steam, or electric coil located at a branch of a HVAC system that supplies air to an
individual room or zone. Reheat coils are commonly used to allow each room or zone served
by a primary air handling unit to add just as much heat as necessary to satisfy the individual
zone's comfort or ambient temperature needs.
RTS
Room Temperature Sensor.
SI units
Système International d'Unités. The international metric system.
slave mode
Default application that comes up when power is first applied to a Terminal Equipment
Controller.
slope
Factor that converts analog values (used by the controller) to a form that the user can
understand (engineering units). Change in y value (engineering units) per unit change in x
value (analog value). Slope and intercept constants are determined by the type of field
input/output represented by the physical or virtual point.