Gas accounting needs traceable history from many of the same EFM sites to facilitate sales invoicing and gas purchase requirements. If the Enterprise-Wide PCAS is to meet expectations, each field site's PCAS Node must reliably communicate the rest of the system. As illustrated in Figure 4, the PCAS Controller is responsible for Connectivity at the site. The IEDs may be as simple as a printer or display terminal or as complex as a gas chromatograph which, by means of the serial communi-cations port on its own controller, can provide the detals of gas quality at a particular site. An IED may also be an existing electronic temperature scanner that monitors the temperatures of an engine and compressor and has serial communications capability.
Connectivity also means reliable information.
The labels on Figure 5 indicate the Connectivity features inherent in the PCAS Controller. Of particular importance is its ability to perform CRC and LRC error detection checks on all communications transactiopns. This feature assures the integrity of the information to be shared, by eay of the enterprise wide PCAS, with the field and office work forces. The Scaleability of a PCAS is related to its capability to be effectively scaled from a small to a large system wihtout suffering from significatnt degradation in performance. Div II Areas Built in keypad for easy operator interface Three level password protection for maximum security.