What is an instrument?
An instrument is a device that measures and control the physical process include pressure, temperature, flow rate and chemical consistency.
Difference between Analog Signal and Digital Signal?
Due to the fact that electrical quantities of voltage and current are able to easily control, manipulate and transmit over long distance, they are widely used to represent the physical variables and transmit the information to the remote locations.
A signal is any kind of physical quantity that conveys information. Audible speech is certainly a kind of signal, as it conveys the thoughts (information) of one person to another through the physical medium of sound. Hand gestures are signals, too, conveying information by means of light. This text is another kind of signal, interpreted by your English-trained mind as information about electric circuits. In this chapter, the word signal will be used primarily in reference to an electrical quantity of voltage or current that is used to represent or signify some other physical quantity.
Analog signal
Simply we can say,a signal which varies continously with time.From the real world itsel we can found out so many examples for analog signals.sound,light etc..But in the case of instrumentaton we are using 4-20 ma or 0-20 ma as analog signals.Here the voltage between controller and instrument is kept constant and taking the current as signal.
Simply we can say,a signal which varies continously with time.From the real world itsel we can found out so many examples for analog signals.sound,light etc..But in the case of instrumentaton we are using 4-20 ma or 0-20 ma as analog signals.Here the voltage between controller and instrument is kept constant and taking the current as signal.
Digital signal
Digital signal is discrete to time. Actually digitally signal is sampled from analog signal.In the conventional method they use two discreet levels for transmitting the signal from instrument to controller. Logic high And Logic low. Relays are used for implement the digital signal transmission. Recently, different types of digital signals are introduced for communication between instrument and controller. Some signals are Profibus, HART, FieldBus. I will explain about each signals in my coming posts.
Digital signal is discrete to time. Actually digitally signal is sampled from analog signal.In the conventional method they use two discreet levels for transmitting the signal from instrument to controller. Logic high And Logic low. Relays are used for implement the digital signal transmission. Recently, different types of digital signals are introduced for communication between instrument and controller. Some signals are Profibus, HART, FieldBus. I will explain about each signals in my coming posts.
No comments:
Post a Comment