Introduction:
When working with SCADA Systems, it becomes apparent that a major component of data acquisition and supervisory based control is the FED equipment – as these will be interfacing with SCADA from the front-end.
This topic is intended for new users, new members to the discipline, to provide more clarity of the components involved.
Definition of Front-End Devices
FED equipment is essentially the interfacing link between the plant (process or factory) and the SCADA. These can form a collective component for decision making (intelligence), in conjunction with the SCADA system, also, these can be the sensors (Data-acquisition), or the actuation (control).
Types of FEDs
FEDs can come in different forms and kinds. The most popular of these are summarized as follows:
A unique type of FED is an OPC server. What makes it unique is its software properties.
Signal Transition between Adroit SCADA and FED.
A simplified, but important summary of the types of signals between transferred in the SCADA process architecture, is being given as follows:
Note – this is a simplified version of this process – with only the essentials being depicted.
Types IO Signals.
Traditionally, IO signals come in two forms, being analog and discrete (aka digital in some FEDs).
Discrete IO is binary in nature, whereas analog signals are continuous in nature.
Communication Networks – the interconnection between a SCADA and a FED
Data acquisition between PLC and SCADA is being accommodated via a Communication Network Standard, running on the rules of a particular. Predefined communication protocol.
In general, communication protocols come classically in one of two types. Below a simplified summary of these, being support by Adroit.
Note: these are only the popular ones. Adroit SCADA can accommodate a wide range of communication protocols.