PLC the codec A/D and D/A

                                   Author: Nuttaphong(www.try-plc.com)


Communication by computer. To communicate information of all types including voice (Voice) character text (Text), Image (Image) and computer information (Data), each data The characteristics of different signals. Divide the actions of the following information.

1. Analog Computer.
Analog is. Continuous data signal (Continuouse Data) is the size of the signal is not constant. Change the size of the signal varies with time gradually. A sign that people can feel like pressure of the water.

2.Digital Computer.
Signal digital data signal is discontinuous (Discrete Data) is the size of the signal constant. Change the size of the signal is suddenly not vary with time. A sign that people can feel like buzze

The relationship of the analog signal and digital signal converter.Contract analog (Analog) and Digital Signal. (Digital), both signal Associated with the codec. (Transducer) for analog connections to your computer. Must be intermediate in Conversion from Analog to change the signal electronically. Called "trans Dew Sir" (Transducer) to convert signals to and fro between Analog and Digital Signal living "the change modulation Converter".
The transducers are two ways.

   1. To convert analog signals to digital signals.
   2. To convert digital signals to analog.

Convert analog signals to digital signals.
Analog to Digital Converter (A / D) signal conversion functions that human perception data is touching the electrical data. To enter into the process. Is the process of obtaining data (Input Unit) is the process Electrolux Electronics. The contracts vary continuously (analog) are converted to digital signals. Without removing important information is the result of ADC is the opposite manner or state level. Often a number of state exponent of 2 is 2, 4, 8, 16 etc. There are 2 basic digital status and called all numbers can be expressed in binary form of binary. As the message. One and zero

The circuit used to convert analog to digital has many types. In general, analog circuit converted to digital (A / D converters) are running about seven species.

   1. Parallel Comparator, Simultaneous, or Flash A / D converter.
   2. Single - Ramp or Single - Slope A / D converter.
   3. Dual - Slope A / D converter.
   4. Charge balance A / D converter.
   5. A / D converters using Counters and D / A converters.
   6. Tracking A / D converters.
   7. Successive - Approximation A / D converters.

Counting Converter.

Convert the analog signal A digital signal. Using the algorithm. Count increasing. Then the results from the count to compare with the desired setting. Analog conversion. A digital signal. Very useful for switching and control equipment. The nature of the transducers in many ways. Each method is an algorithm. Speed of work. And using different hardware devices with

Indications of a specific codec A / D (A / D SPECIFICATIONS).

Indication only to tell the capability of the converter typically has several words, such as precision, accuracy And accuracy in a straight line. That these values are based on characteristics of each circuit. But there are indications that not only one of more depending on the nature of the circuit. The error between the actual analog signal. The value of the digital replacement value (the value of Output of A / D converter), called Quantizing error will cost approximately 1 / 2 digit minimum (LSB) of the codec, which also signifies the accuracy again. The one with values. Another important parameter for the A / D converter is conversiontime. Or the time for the codec. This is the second time in about 10-9 to 10-3 seconds, depending on the type and number of bit converter Rangsiman Chaichana
convert digital signals to analog

Digital to Analog Converter (D / A) functions convert the results of signal processing power. As a signal that people can perceive tactile representation of data (Output Unit) digital-to-analog conversion process, which is the signal level. Or status of one (usually the second state) or digital signal. As a signal that does not limit the number of status Or analog modem to guide the process of converting computer data. The frequency. To be sent via telephone line twisted pair in the circuit working for this function is called a digital-to-analog converter (DAC) with basic digital-to-analog conversion opposite the analog-to-analog conversion if the analog-to-analog. converter (ADC) is placed in circuit communication to the digital signal sent out from the DAC. To match the digital signal to import if the DAC is placed in the circuit to the ADC signal Analog Block exports will match the signal Analog Block import digital signals as binary appears as a message length of 1 and 0. This does not mean to read but the DAC using binary decoding digital signals, so the results appear meaningful. This may be sound, image, music and movement mechanisms.

Circuits convert digital signals to analog 2 as follows.

   1. The total flow (weighted-resistor).
   2. Infrastructure for R-2R (R-2R network).
Integrated flow (weighted-resistor).

Features of the D / A integrated flow.

   1.'ll Need all the input resistance of the digital signal.
   2. The resistance is the input of all bits are equal to a maximum digital output level.
   3. Forces moving full scale output is equal to a maximum digital output level.
   4. LSB has a weight 1 / (2n-1) when n is the number of bits of input.
   5. LSB change the output electromotive force changes to 1 / (2n-1) when V is a digital signal.

infrastructure for R-2R (R-2R network).

Structure of the circuit shown in Figure 3 shows the structure of the circuit D / A as an R-2R.