Lesson 3 SCADA

SCADA WHAT IS IT Today’s Supervisory Control and Data Acquisition (SCADA) system incorporate Programmable Logic Controllers (PLCs), Human Machine Interface (HMI) workstations and Network Communications (Networks) systems into a complete integrated system. Each of the major components requires one or more form of programming form program logic to configuration to process graphic displays to communications configuration. This class will focus on the 3 major components of the SCADA system. Let’s begin………..

Preface Today’s SCADA systems incorporate PLCs, Human- Machine Interface (HMI) workstations, and network communication systems into a complete integrated systems. Each of the major components requires one or more form of programming from program logic to configuration to process graphic displays to communication configuration.

SCADA preface continued SCADA systems are global; every automated system in the world involves some form of process controller and user interface facility. These systems can range from a single controller that monitors and controls a small set of processes with a single workstation for user interfacing, to large geographical systems of controllers, user interface workstations, server computers, and both local and system wide communication networks.

Elements of SCADA Software Programming software for Supervisory Control and Data Acquisition (SCADA) systems involves: SCADA operations user workstation SOW software Programmable Process Controller (PPC) software In Addition, SCADA systems require programming of an interface between the user workstation computers and the programmable controller equipment.

SCADA Software Example

SCADA Software Example Consider a typical material handling system to illustrate the different processes involved in a SCADA system. A material handling system such as a tennis manufacturing line consist of stages of areas of operation, each of which can be considered complete subsystem. The process operation are specific to that area, such as ball making (not shown), ball stamping (not shown), grouping for packaging (shown in figure and explained in next slide), and packaging into boxes (shown). Within the subsystem there are field signals to the PPC, control signals from PPC, and communications to and from the SOW. Users can interact with the system via the SOW, issuing commands, adjusting setpoints and parameters, and responding to alarm conditions.

SCADA Software Example Application Example: Grouping tennis ball for packaging The counter in the figure counts the pulses from a sensor that detects the passing of a ball and produces a sequence of logic levels (digital waveforms) on each of its four parallel outputs. Each set of logic level represent a 4 bit binary number (HIGH=1 and Low = 0). As the decoder receives these waveforms, it decodes each four bits and converts it into the corresponding decimal number in the seven segment display. When the counter gets to the binary state 1001, it has counted nine tennis ball, and a new box is moved into the conveyor belt. Then the counter goes back to 0000 state and the process starts over.