Answer / surendra singh tanwar

I/O are required to convert the process value or status in
to a formet which can be communicated to the controller and
v/v controller to processe

Answer / delta_v

Remember that from field instruments the signal sent are only process data (example temperature, pressure); these data can't be read by the controller, hence it will become useless.
That is why IO cards are used to convert these to a readable signal which is 4-20mA.




"You cannot measure, what you cannot control"

Answer / makinde motunrayo

why we don't use I/O directly with controller.
The controller here is PLC, I/O is not use directly because of space the back-plane will occupy . i.e Organisation of instruments from field to the controller.

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