Difference between RTU & PLC and also SCADA VS HMI

[THED]

Hi,

Can someone please clarify whats the difference between RTU (remote terminal unit) and PLC (programmable logic controller)?

As well as difference between HMI & SCADA? I am so confused.

Isn't RTU basically PLC? Thanks.

[Thomas-B · Accepted solution]

Hi, 

Hopefully I can clear things up for you. RTUs (Remote Terminal Units or Remote Telemetry Units) and PLCs (Programmable Logic Controllers) perform similar functions, as they share certain functionalities. However, RTUs are often considered for gathering telemetry data over large geographical areas, because they use wireless communication. PLCs are commonly implemented in situations where local control is needed, like assembly lines and ammusment rides because they are designed for multiple inputs and outputs. 

Your confusion with SCADA and HMI is common. HMI (Human Machine Interface) is a part of SCADA (Supervisory Control and Data Acquisition). SCADA is used to monitor or control specific portions of a larger system. For instance, a SCADA system may be used to optimize and control a water treatment plant. An HMI is just a user interface of the SCADA system. For example, if someone wanted to change the rate at which is certain measurement were taken, they would use the HMI. 

I hope this helps. If you want more information you can peruse the information on the two links below. 

http://www.differencebetween.net/technology/industrial/difference-between-plc-and-rtu/

http://www.differencebetween.net/technology/industrial/differences-between-scada-and-hmi/

Best Regards, 

Thomas B.

[THED]

Thank you so much ! 😃

[THED]

One more question, if I connected PLC to field device with a HMI computer software that enable me to monitor and control the field devices on the local field. Is it still considered as a SCADA or that is HMI?

[Thomas-B]

Hi THED, 

I am glad that I was able to clear some things up for you. Regarding your last question, from what I understand  from your explanation of the setup, it sounds like the system as a whole would be considered a SCADA system. The HMI portion is simply the interface for the user, used to access the PLC on the field. 

[Dino88]

Hello--> Please Clarify the System Communication protocols used in now a days and why? 

[Dino88]

Both the HMI & PLC/DCS considered as SCADA????

[Dino88]

Both the HMI & PLC/DCS considered as SCADA????

[Dennis_Knutson]

An HMI and a PLC would be considered different parts of SCADA.

I would suggest you use Google to find your answers as your questions are totally unrelated to this board.