Computer-directed distributed control

Process control systems have increased in complexity as electronic control systems were replaced by computer-directed distributed control systems (DCS). Gone are the control rooms full of panels and gauges, switches, meters, and charts. They have been replaced with something that looks like a space shuttle control panel. Processes run faster, more safely, and produce higher quality product using the latest methods of statistical quality control. Improvements in information technology make it possible for the employees to know almost immediately what each piece of equipment under their control is doing. 

Control System Included in this classification are Supervisory Control and Data Acquisition Systems (SCADA), Distributed Control Systems (DCS), Statistical Process Control systems (SPC), Programmable Logic Controllers (PLCs), intelligent electronic devices, and computer systems that control manufacturing equipment or receive data directly from manufacturing equipment PLCs. 

Modern process MS analyzers are controlled by microcontrollers and PC computers. Many incorporate internal processors that permit stand-alone operation, with a PC only required for initial configuration. The processor then handles all measurement and quantitation, as well as data interfacing, fault diagnosis and alarming, and calibration. Process mass spectrometers can be directly interfaced to plant distributed control systems, programmable loop controllers, or other process control systems. 

The improvements in the computer technology led to the creation of Direct Numerical Control (DNC). DNC involves a computer that acts as a partial of full controller to one or more NC machines. Further to that, improvements in the field led to the creation of Distributed Numerical Control, where several CNC machines are linked together inside a network allowing the gathering and storing of upstream and downstream shop-floor information. In Figs. 8 and 9 the differences in the architecture of Direct and Distributed Numerical Control are presented. 

Computer-Aided Manufacturing, Fig. 8 Direct numerical control (left) and distributed numerical control (right) (Seames 2002)... 

The chip is a standalone microsensor system that does not need any external measurement equipment for sensor control and readout. The sensor system chip has been connected to a computer via an f C-to-USB converter box, i.e., in this box is a microcontroller that translates the I C format coming from the chip into USB format for the computer or laptop. The power supply of the chip is also provided by the USB connection. The sensor system can be read out directly by a microcontroller and is, therefore, well suited for handheld devices or distributed sensor networks. 

Computer systems are used worldwide in the pharmaceutical industry and have direct bearing on product quality. The purpose of validation is to demonstrate that the intended product manufactured, packed, or distributed using a computerized controlled system will meet the safety, efficacy, and potency requirements per the individual monograph. 

The load distribution can be computer-optimized by calculating compressor efficiencies (in units of flow per unit power) and loading the compressors in their order of efficiencies. The pressure controller (PC-22) directly sets the set points of SC-21 and SC-23, whereas the balancing controllers (FFC-22 and FFC-24) slowly bias those settings as they follow the total H2 generation of the electrolyzers (FT-4). The flow ratio controllers (FFCs) are also protected from reset windup, as was explained in Section 2.5.4. 

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