Hmi vs. Scada

Topics: Programmable logic controller, Control, Graphical user interface Pages: 2 (613 words) Published: July 14, 2013
1. What are the differences between HMI and SCADA?
In large industrial structures, it is impractical or even impossible to control the individual parts of the system because, in most installations, the parts are often located very far from each other. Thus the need arises to monitor and control them with SCADA and HMI. The main difference between SCADA and HMI is their scope. HMI is actually just a part of the larger SCADA system. Without SCADA, the HMI would be pretty much useless. “SCADA” stands for “Supervisory Control and Data Acquisition,” which is an integrated system that is used to control and monitor the workings of the individual parts of the plant. The SCADA often controls pumps, fans, and other machinery along with their other characteristics. The controlling mechanisms are electronic circuits known as programmable logic circuits or PLCs. The PLC controls the machine as well as polls the sensors for data. The data is then sent to the control room. In the control room, the operator needs to make sense of the data as well as issue commands like turning the machines on or off. This is where the HMI, or Human Machine Interface, comes in. The HMI is usually a graphical layout of the entire system with gauges, lights, and controls situated in the corresponding locations of the machines. The gauges show the normal range of operation as well as the abnormal range so that the operator knows if the equipment is within the accepted operating range. The lights may indicate if the machine is working or not, as well as the occurrence of faults. The controls send the instructions to the PLC, which in turn control the machine. SCADA is a complete control system while the HMI is what the human operator works with it.

2. Give at least 3 advantages of HMI.
Alarms (Real Time / Historical)
Viewing alarms will help the operator to locate and react faster to any malfunction of any anomalies. Some of the alarms could be of preventive type, for example to create a...
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