DCS & PLC I/O list preparation

Draw up a table.

• Label column 1 "Device"
• List each real-world device in column 1 that the system is intended to interact with.
• Label columns 2, 3, 4 and 5 with the headings "DI, DO, AI and AO" respectively
• Consider the number of inputs and outputs needed by each real-world device. Enter these numbers into columns 2, 3, 4 and 5 as appropriate. Repeat until all real-world devices have been considered.
• Total the columns at the bottom.

How to calculate DI,DO,AI,AO? can u please tell me what are all the instruments require DO, AO? from which instrument DI, AI signal goes to DCS/PLC?

None of that can be seen from here as it depends upon the real-world equipment to be selected locally.

A level of judgement is needed locally to decide whether to use all the available features of the real-world equipment, or only some of them. For example, a solenoid-operated valve in a process pipeline may have been fitted with both an open limit and a closed limit switch; one might want to know that the valve is positively closed though its open condition may be inferred from process parameters such as flowrate in the pipe. In this case, rather than one digital output to the solenoid and two digital inputs from the limit switches, one might want to use only the closed input and discard the option of the open one, inferring "open" in the DCS by using "not closed" from the inverted "valve closed" input. Discarding the "open" input also discards the option of "not closed and not open" (meaning "valve travelling") being displayed, and also the option of any alarm function on the travelling time in each direction that could be interpreted as a maintenance call-out requirement on the valve.

So it depends upon what is wanted from the system, which is usually defined in a Functional Specification document at an early stage; the Functional Specification cannot be seen from here.

Hire someone who knows what they are doing. The questions presented here demonstrate your complete lack of knowledge of the task at hand.

Refer the PID and the control narratives . You will get the required inputs