What is the difference between PLC and RTU and why usuallly do see PLC with DCS and RTU with SCADA?

plc is a programmable logic controller    RTU is remote terminal unit and DCS is distribute control system , scaada consists of rtu and mtu (master terminal unit), dcs and LTU for long distance plc used one master cpu but dcs used more masters cpu by dcs program connect in on server

From My Work Experience and theoretical Understanding RTU  it can be used to Monitor Some kind of   Process Thats available in The Work enviroment (Oil Well Heads, Pipe Line, Electrical Substation And Water Treatment Process), And its Depend on The Customer Need you can Control The Application When You Need For Example ( Controlling VSD Systems, ESD for Unsafe Act Enviroment,And Also you Can Put Your Own Script (using Basic, C language) ,But  The RTU it Can Not Act Fast Enough in Very Complicated Scenario Like PLC , using Ladder Programming in PLC (Yokagawa, AB,Schenider,Siemens,..etc) And This Option is Not Mostly Available in Starndard RTU unless Requried by Customer, Because Mostly They Are using RTU in Very Simple Scnearios Unless Customer Choose to Modify, PLC Can do The Work OF RTU very easy, Keeping Up With Different Kind of Protocols Like RTU (DNP3,Profibus,Canopen, MODBUS ASCII,MODBUS PLUS,MODBUS RTU, MODBUS TCP/IP),PLC Also it  Can be Attached to Any SCADA Systems, Only Configure The Tag Address u Need to retrieve The Data From it, Historical Server, And Screen Builder for Animating The Output from The PLC  And You Will Monitor What ever you have in Your Screen about What Plant Process Through Your PLC, So its Not Standard That Why RTU is Attached to SCADA And PLC Attached to DCS, its Depond on Application That Customer Need.

 

Your Welcome Bro

Hello, PLC is “Programmable Logic Controller”, its main function is performing plant control loops, mathematical calculations, sequence handling, interlocking….etc.
Communication options was integrated and embedded in PLC to enable data exchange with other devices or with SCADA “Supervisory Control And Data Acquisition” however its main function is to control.
RTU is “Remote Terminal Unit”, from its name you find out that its function is to transfer data “Remotely” which have more powerful communication capabilities, options and varieties but without Logic (or very simple logic in some models) Regards,

RTU ( remote terminal unit ) is used mainly for telemetry and relaying data to the SCADA systems , it doesn't support control loops or algorithms unlike PLC (programmable logic control) which acts mainly as a local controller and can act independently and can relay data to DCS .
the RTU also uses wireless communication which makes them more suitable for use for wider geographical telemetry .

PLC is normally use for local plant monitoring / controlling RTU (remote terminal unit) is normally use for wide range of control / monitoring.
PLC usually use with HMI and RTU use with DCS to become SCADA

plc:programmable logic controller & RTU : remote terminal unit and DCS : distribute control system , scaada only screen used with plc , dcs and RTU for long distance plc used one master cpu but dcs used more master cpu by dcs program connect in on server

Since the evolution of technology, there is not more difference, we see between PLC and RTU.
PLC was initially stand-alone controller with Boolean Control; whereas RTU was designed to work with SCADA.
Today, you can find hybrid PLC/RTUs, if you can search on internet.
PLC and RTU both are control for local control, but RTU will send data to main server of SCADA.
Further, DCS is also stand-alone controller, which directly deals with process control, and PLC can be integrated into DCS, then DCS will function as SCADA.
Now, in SCADA, RTU (Remote Telemetry Unit) is working as Local Control for specific region.
and Due to failure of communication RTU also work alone or vice-verse.
PLC is working with Boolean logic and RTU is working with Protocols.

Well RTU is moajorly used for SCADA purpose , less PLC programmind and more just for just Remote control and monitoring...
You can find RTU with SCADA protocols most of the time (DNP3,IEC101,104,103, Modbus) and there are fewer RTUs supporting Profibus and other Industrial Automation protocols and RTU is less used for fast plc coding and things like that.
Well for PLC just viceversa ...more for industrial automation and control of process (DCS).

PLC and DCS are controlling Systems, get data and output some controlling function according to control program and set point from user.

While RTU is data collection System it uses with SCADA to monitor this data from Remote distancees.

 

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 functionalists.
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 amusement rides because they are designed for multiple inputs and outputs.

 

plc is a programmable logic controller & RTU is remote terminal unit PLC is “Programmable Logic Controller”, its main function is performing plant control loops, mathematical calculations, sequence handling, interlocking….etcPLC is normally use for local plant monitoringRTU is “Remote Terminal Unit”, from its name you find out that its function is to transfer data “Remotely” which have more powerful communication capabilities