SC unit uses a multilevel Client-Server type structure in order to make the control process extremely quick and able to realize sophisticated applications for data presentation and more. The use of intelligent cards allows the whole control process to be distributed on more independent levels, each one completely autonomous and controlled by the upper level, at the same time.
DATA ACQUISITION PHASE
As shown in the figure the lowest level of the structure includes the real-time data control and acquisition functionalities, carried out by intelligent data acquisition cards. Each card manages the acquisition of the data in a completely autonomous way, sending them to the SC-MCC card, which carries out the post-acquisition analysis (second level of the structure). In detail, the function of the SC-MCC card is to centralize the data acquired and control any possible alarms. Then, the data processed by the SC-MCC card are reorganized according to the standards of MODBUS protocol and made available on the Ethernet network (TCP/IP or IP/UDP), in order to be read by PC stations able to display the data of the sensor readings.
CONTROL AND SUPERVISION PHASE
While starting the system, the SC-MCC card checks the system consistency (presence and identification of the cards) to transfer to the intelligent interfaces the related application software. Moreover, the SC-MCC card manages the application software updating of the intelligent peripherals also in a remote-controlled mode, through FTP or TFTP procedures. In its turn, the SC-MCC card is controlled and configured by a network PC station, on which the SC-View configuration software (supplied with the SC unit) is present. The unit configuration process includes either the data for the operation of the data acquisition interfaces or the operation of the centralization and acquisition process performed by the SC-MCC card itself.
A client is a computer system that accesses a (remote) service on another computer by some kind of network.
A server is an application program that accepts connections in order to service requests by sending back responses.
Client-server is computing architecture which separates a client from a server, and is almost always implemented over a computer network. Each client or server connected to a network can also be referred to as a node. Each instance of the client software can send data requests to one or more connected servers. In turn, the servers can accept these requests, process them, and return the requested information to the client. Although this concept can be applied for a variety of reasons to many different kinds of applications, the architecture remains fundamentally the same. most cases, a client-server architecture enables the roles and responsibilities of a computing system to be distributed among several independent computers that are known to each other only through a network. This creates an additional advantage to this architecture: greater ease of maintenance. For example, it is possible to replace, repair, upgrade, or even relocate a server while its clients remain both unaware and unaffected by that change. This independence from change is also referred to as encapsulation.