whats difference between DDC, DCS & PLC ?

plz use google

I think it is the size of the box plc small, ddc medium, dcs large.

Are u a technical person or mad ??????????

DDC : DDC is a universal controller where both analog and digital input/outputs are combined in one controller card also it is specially designed for the HVAC ( Heat ventilation air conditioning) design which are used for air handling unit. it's cost is lower than compare to PLC and DCS, it uses profibus and modbus as a communication protocol which are very speedy responds.

PLC : plc is mainly design for small applications, cost is higher compare to DDC. it is only one conroller, communication protocols are open so it can connect with any controller, programming language is ladder logic and functional block diagram whcih work on relay logic.

DCS : distributed control system which works on multiple controller, and nos of controller are attached with system, cost is very high. communication protocols are open, mainly used in continuous plant and very highly efficiency plant.

please go to website www.plctalk.net,& www.control.com & http://cr4.globalspec.com/thread/14677/whats-difference-between-DDC-DCS-PLC & http://tunthai.multiply.com/journal/item/2387/CR4_DDC_Direct_Digital_Control_vs_Distributed_Control_SystemProgrammable_Logic_Controller_DCSPLC

http://www.allinterview.com/showanswers/69909.html( u will get very good answers)

hope these sites may help u

Shrimant Shanbhag, Bangalore, India

1.Direct Digital Control refers to the ability to control HVAC devices via programming

2. PLC Simplified with limited logic control for like a machine or simple process with limited interlock logic

3. DCS is concerned with huge multiple logic controllers with >1000 of inter lock for process of power plant or refineries or any process Industries)

In essence they are application specific to different processes but they all operate on the same principle such as programming logic and digital