Microcontroller - Types :

My favourite microcontrollers (µC) belong to the 8051-family and
cover a 20-pin 89C2051 up to a 84-pin 80C517A.
A short overview of the performances of these mcs you can find in the menu DEVELOPMENT.

   The Operation of a Microcontrolled Device :

The operation or remote control can be done via keyboard, via RS232-Interface or simply by terminals (24V-inputs).
As a feedback of operation can serve e.g. LCD   (also LED iluminated), LEDs or readable (also non volantile) History-Data.

   Interfaces :

A microcontroller from 8051-family is equipped with 1 to 2   RS232-Interfaces 'on board (that means 'on chip')'.
Simply emulating one can drive e.g. I²C, GPIB and some others.
USB now is available with intelligent interface chips (like 7210 for GPIB in former times)

Optional there is available an adapter from Ethernet (10MBit/s or 100MBit/s) to RS232 incl. power supply (230Vac) and an alu-metal housing.
This adapter enables reading with a standard browser (that means without special personalized programm) on a pc your microcontrolled device / or configure / or servicing etc..

   Memory :

In a nonvolantile memory one can store sets of e.g. history data, configure data etc.
But a battery is not necessary !
There are EEPROMs available, which are overwritable with min. 1 Million cycles, or a so called NOVRAM, which writes its RAM-content only in case of power fail automatically into its backgrounded EEPROM.
Real time clocks are optional available too.
They provide a history profile which can be read or downloaded by service persons etc.
Possible is further a 'Security Flash Product', this is only readable by feeding a 64-bit password

   Operational Security :

The pcb layout for the microcontroller will be designed for best proofness against transients; also avoiding the highest possibel clock rate, if it is not necessary .
Special protection design (e.g. overvoltage-diodes, resettable fuses are used every time).
The programming interaction itself will be controlled in most cases with an internal hardware watchdog timer.
The necessary (e.g. first failure-) security of the industrial control   can be certificated by german TUEV (optional this can be served).