Programmable Logic Controllers Assignment Example | Topics and Well Written Essays - 750 words

Programmable Logic Controllers - Assignment Example The RES instruction is used to cancel the SET instruction, hence putting the PLC off. In the contemporary society, electronic devices are used in variety of ways. Electronic devices which make use of microprocessors rely on signals to understand information. Signals are available in two forms, i.e. Digital and analogue. Electronic devices can only understand information that is in digital format, and hence the analogue signals are meaningless in such devices. For this reason, the conversion of analogue to digital signals is essential, especially considering that most real life situations lead to the production of analogue signals. The analogue to digital conversion of information, changes the format of the information, without altering its content. Microprocessors are used for the conversion of the analogue signal to digital. The principle used in the conversion of analogue signals to digital signals by the microprocessor is the voltage variation. The microprocessor used sensors, which detect the incoming analogue signals, and translate them into voltage levels. For instance, the translation of temperature of 0 – 1000c, leads to the assignment of 0 volts to 00c, and 5volts to 1000c. Any value that is above 0volts represents an HIGH, and hence microprocessor can show the actual value, depending upon the number of levels the microprocessor can represent. The resolution of the A/D converter refers to the number of intervals which can be divided from a certain analog input range. Since the interpretation of the analogue input (e.g. temperature) requires assigning of voltage levels, the number of levels which can be represented is determined by the resolution. Resolution of A/D converter is represented in bits, for instance, an n-bit A/D converter has a resolution of 1/2n. The word length, as used in the microprocessors refers to the