PLCs (Programmable Logic Controllers) are the traditional way to solve the interface between software and hardware sensors. This is done in industrial computing and control all the time (Factories, manufacturing machines, robotics, etc). The sensors and actuators are connected to the Digital/Analog Inputs and Outputs of the PLC. The input signals are converted into variables (with ADC) that can be read like any other variables. The output variabels are converted back into the appropriate valtages and currents (0-10 VDC or 4-20mA). The I/O modules also do error, short circuit, wire break, etc. checks. Basically PLCs take out the hassle of having to build the hardware interface between the real world to the software.
Most of them are programmed in a graphical language called Ladder diagram (like relay logic dagrams in software). Some of the more advanced ones can be programmed in C or other 3rd generation languages. There is actually a standardised set of languages to program them, Structured Text is the one that is most C/Pascal/Basic like (see IEC 61131-3). There are libraries etc to support all the conventional control issues and yes you can build your own. See companies like Siemens Automation and Drives http://www.siemens.com/, Rockwell Automation http://www.rockwellautomation.com/, Bernecker & Rainer Industrial Automation http://www.br-automation.com/, Schneider http://www.schneider-electric.com/ for more information.
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PLCs (Programmable Logic Controllers) are the traditional way to solve the interface between software and hardware sensors. This is done in industrial computing and control all the time (Factories, manufacturing machines, robotics, etc). The sensors and actuators are connected to the Digital/Analog Inputs and Outputs of the PLC. The input signals are converted into variables (with ADC) that can be read like any other variables. The output variabels are converted back into the appropriate valtages and currents (0-10 VDC or 4-20mA). The I/O modules also do error, short circuit, wire break, etc. checks. Basically PLCs take out the hassle of having to build the hardware interface between the real world to the software.
Most of them are programmed in a graphical language called Ladder diagram (like relay logic dagrams in software). Some of the more advanced ones can be programmed in C or other 3rd generation languages. There is actually a standardised set of languages to program them, Structured Text is the one that is most C/Pascal/Basic like (see IEC 61131-3). There are libraries etc to support all the conventional control issues and yes you can build your own.
See companies like Siemens Automation and Drives http://www.siemens.com/, Rockwell Automation http://www.rockwellautomation.com/, Bernecker & Rainer Industrial Automation http://www.br-automation.com/, Schneider http://www.schneider-electric.com/ for more information.