| Custom Industrial Controllers Outperform PLCs | | | | custom-developed by Orchid Technologies to solve a |
| Written by Paul Nickelsberg, President and CTO of | | | | specific industrial control requirement. Controller size, |
| Orchid Technologies Engineering and Consulting, Inc. | | | | safety, and reliability were paramount concerns. |
| Programmable Logic Controllers, PLCs, are used | | | | Cryogenic pump control makes use of highly |
| extensively for industrial control applications. PLCs | | | | specialized pressure and temperature sensors. |
| provide the designer with a general processor | | | | Cryogenic pump control requires the execution of |
| architecture, a general input / output architecture, a | | | | specially timed operational sequences. Motor |
| general mechanical architecture, and a general | | | | systems, heating systems, liquid flow systems, must |
| software development architecture. Industrial | | | | be precisely controlled. Commands are received |
| designer engineers, factory automation engineers, or | | | | from upstream factory automation equipment. |
| industrial controls developers may take advantage of | | | | Operator indicators provide early emergency-situation |
| generalized solutions for their particular needs. | | | | warnings. |
| There are times when the generalized architecture of | | | | Based upon a low-cost Freescale HCS12 processor, |
| PLCs is unsuitable. Perhaps the equipment to be | | | | the cryogenic pump controller replaced thousands of |
| controlled is sold in volume. Perhaps the equipment | | | | dollars of general purpose PLC equipment. The |
| to be controlled must fit in a limited volume or | | | | single circuit board custom controller provided RS232 |
| space. Perhaps the equipment to be controlled | | | | Communications, Network Communications, Real |
| requires the use of specialized sensors and | | | | Time Clock services, AC Motor Control, AC Heater |
| instrumentation. Perhaps the equipment to be | | | | Control, two cryogenic temperature sensing channels, |
| controlled requires simplified interconnection | | | | two low pressure sensors, and general purpose IO. |
| mechanisms. A customized industrial controller can | | | | Custom programming efficiently executes complex |
| save cost, save space, use specialized sensors and | | | | pump control sequences including purging, |
| simplify deployment when compared with general | | | | regeneration, temperature control and error |
| purpose PLCs. | | | | detection. The single board controller is housed in a |
| The cryogenic pump controller shown below was | | | | small water-proof NEMA-rated steel box. |