By Paul Nickelsberg
Designers use Programmable Logic Controllers (PLCs) extensively for industrial control applications. A PLC features a general processor architecture, a general input / output architecture, a general mechanical architecture, and a general software development architecture. Industrial designer engineers, factory automation engineers, and industrial controls developers can meet their needs with generalized solutions. However, there are times when the generalized architecture of a PLC is unsuitable.
Perhaps the equipment to be controlled is sold in volume. Perhaps the equipment to be controlled must fit in a limited volume or space. Perhaps the equipment to be controlled requires the use of specialized sensors and instrumentation. Perhaps the equipment to be controlled requires simplified interconnection mechanisms. A customized industrial controller can save cost, save space, use specialized sensors, and simplify deployment when compared with general purpose PLCs.
Orchid Technologies custom developed the cryogenic pump controller (photo below) to solve a specific industrial control requirement. Controller size, safety, and reliability were paramount concerns. Cryogenic pump control makes use of highly specialized pressure and temperature sensors. Cryogenic pump control requires the execution of specially timed operational sequences. Motor systems, heating systems, and liquid flow systems must be precisely controlled. Commands are received from upstream factory automation equipment. Operator indicators provide early emergency-situation warnings.
The cryogenic pump controller is based upon a low-cost Freescale HCS12 processor. It replaces thousands of dollars of general purpose PLC equipment. The single circuit board custom controller features RS232 communications, network communications, real time clock services, AC motor control, AC heater control, two cryogenic temperature sensing channels, two low pressure sensors, and general purpose IO. Custom programming efficiently executes complex pump control sequences — including purging, regeneration, temperature control, and error detection. The single board controller is housed in a small water-proof NEMA-rated steel box.
Customized industrial control solutions — such as the cryopump controller — costs a fraction of what a comparable PLC solution might cost.
Paul Nickelsberg is President and CTO of Orchid Technologies Engineering and Consulting, Inc.
Orchid Technologies designs and fabricates custom solutions for demanding control needs.