![]() ![]() The use of PCs also meant that the options for viewing history were considerably easier. ![]() This was further modified for process control to become OLE for Process Control (OPC), which is still used at the time of writing. This data exchange ‘language’ was termed Dynamic Data Exchange (DDE), and subsequently developed into Object Linking and Embedding (OLE). The advantage of the ‘Windows’ based systems was that information was exchangeable in the same way that today’s personal computer user can freely exchange data between Word, ‘Excel’ and ‘PowerPoint’. This provided a standard platform for the earlier digital control systems, as all the instrument companies needed to work in a common format. all of which are in prolific use today (see Figure 5.6.5).Ī giant leap forward occurred in the late 1980’s with the introduction of the PC and the Windows screen environment and computer operating system. Supervisory Control And Data Acquisition (SCADA) systems, and.These Digital Control Systems led to the development of: As technology progressed, the I/O device moved out to the plant, and the amount of cabling to the control room was reduced, but was still significant.This meant that on a large plant, the cable installation and management was an important issue, in terms of its physical volume and corresponding cost. In the beginning, the I / O devices were in the plant’s main control room, and each individual piece of equipment was connected to the main control room by its own individual signal cable.Each of the I / O manufacturers had a unique means of achieving this, which meant that the systems were not quite as compatible as had been intended. An Input / Output (I / O) device was required to ‘translate’ between the two. A personal computer (PC) cannot accept the raw instrument signals (4 - 20 mA, 0 - 10 V) from a control device.These complex and expensive controllers were often found in large petrochemical plants where accurate control of the process, as well as intrinsic safety (the absence of sparks which could initiate a fire) was essential. Stand-alone, single loop controllers date back to pneumatic controllers, which, through the ingenious use of flaps and nozzles, could approximate the basic PID functions. The rate of advancement in controls technology surely means that some of the following comments will be redundant when read. ![]() The development rate of the computer chip and its impact on all aspects of life is well known. This definition includes the basic, single- and multi-loop controllers commonly found in process industries where a condition is read by a sensor, compared to a set point in the controller via some mathematical routines performed to determine the corrective action required, followed by an output of an appropriate signal. It may be appropriate to end Block 5 with a broad look at the involvement of computers in control systems.Ī dictionary definition of the term ‘computer’ is ‘a programmable electronic device that can store, retrieve, and process data’.
0 Comments
Leave a Reply. |