I'm about to use siemens pxc controller in one of my projects, bit before that I need to know its advantages and disadvantages.
Can you help me please?
Is your query specific to the controller you are referring, or are you asking about using a PLC in general?
If you are asking about the specific controller, I'd suggest that it probably really has no advantage or disadvantage over any other industrial quality PLC, unless you are already familiar with the development software and peripherals.
If you are asking about PLCs in general;
The first PLCs replaced hard relays, timers, drum sequencers and the like. Later versions provide lots of other process control functions such as PID, flow totalizing and the like. New industrial grade PLCs are able to perform just about any computing function that you would ever need to support most manufacturing processes. They also provide for connection to an operator interface (HMI) terminal. As a rule, they are extremely reliable and some conform to environmental and SIL ratings including redundancy if needed.
So- A quick answer to your question;
Advantages include that since the logic is software, changes can be made quickly and without making hardware changes to a control panel. I/O modules can be added to provide for a large number of discrete, analog, and communication options. Most PLCs now can communicate over non-proprietary open networks so information can be retrieved from them easily.
The main disadvantage I would identify here is that they require a modicum of knowledge to use the development software, and that software is sometimes pricey.
Brad Waybright