ABB Instrumentation”sTZIDC electro-pneumatic positioner mounts to pneumatic linear or rotaryactuators. The positioner is designed for 4-20 mA control systems andoffers a compact design, modular construction, and an advantageouscost-performance ratio. The positioner automatically adapts its controlsettings to final control elements, such as valves, offering optimalcontrol behavior. Modularity permits future enhancements by variousoptional retrofits and plug-ins. An I/P module within the TZIDCpositioner adjusts a 3/3-way valve that regulates airflow forpressurizing or depressurizing the actuator to maintain position. Whenthe actuator reaches the position set point, the 3/3-way valve closesin its center position to minimize air consumption. The positionercomes in four different pneumatic versions: single-acting ordouble-acting actuators, each with a “failsafe” or “fail-freeze”function. The positioner has a built-in operating panel providing atwo-line LCD and four pushbuttons for optimal local configuration,simple commissioning, and operational monitoring. Alternatively,communication capabilities permit remote configuration. TZIDC modelsare available with direct serial communications, as well as HART,PROFIBUS PA, and FOUNDATION fieldbus protocols. Additional digitalinput and output functions expand the positioner’s capabilities. Thedigital input can activate various protective functions in the devicevia the process control system. A digital output allows the sending ofcollective alarms or fault messages.