The CAL 9500P is West Control Solutions' 1/16 DIN programmable temperature and process controller, designed for applications where the setpoint must follow a defined time-temperature profile rather than a single fixed value. It stores up to 31 independent programs — each a sequence of ramp and soak (dwell) segments — sharing a pool of 126 total segments. A ramp segment linearly changes the setpoint from the current value to a target over a specified time or rate; a soak segment holds the setpoint constant for a defined duration before the next ramp begins. Together they build the complex heat-treatment, curing, annealing, and sterilization profiles common in environmental chambers, ovens, autoclaves, and laboratory equipment.

How does dAC approach control differ from standard PID?

The Derivative Approach Control (dAC) algorithm actively manages the controller's approach to setpoint — the phase where conventional PID controllers typically overshoot as the integral term unwinds accumulated error from the ramp phase. dAC predicts the overshoot trajectory and reduces output power before the process variable reaches setpoint, minimizing the temperature excursion that degrades heat-sensitive materials and extends cycle time waiting for stabilization. This is particularly valuable in multi-segment profiles where overshoot on one segment delays the start of the next, compounding across the entire program.

How are programs created and managed?

Programs can be created directly from the front panel using the rubberized membrane keys, or via CALgrafix PC software — a drag-and-drop profile editor that also provides real-time chart recording, virtual instrument display, datalogging, and the ability to clone complete configurations across multiple controllers. The Modbus RTU interface (RS232 + RS485) enables integration with PLC and SCADA systems for remote program selection, start/stop control, and process value readback. FM approval (FM 3545) qualifies the CAL 9500P for use in North American combustion safety applications.