PLC program can be changed. Now most of the microcontroller (internal FLASH ROM) are available online–burning program, change the program so that it functions with PLC is the same. Of course, there is a curing process. You can no longer change the program like this.
PLC chip, its main advantages:
1: stable photoelectric isolation due to I/O port internal drivers, so many stronger anti-interference ability.
2:I/O of driving ability is stronger, can directly drive 24V relay sucks and shuts.
3: man–machine interfaces, and in some occasions, are common on the market and now develops software and interfaces, so relative to the single–chip microcomputer and its development cycle was much shorter.
In addition, the PLC costs are much more expensive than single–chip. Therefore, to see what, if on a single chip, enough, no need to consider the use of PLC.
PLC ONE 