DATA_v1

DATA_v1

Data Checking
1. Data Verification - It is to check the data for error
  1. Proof-Reading
    1. The person entering the data simply reads through what they have entered to check it is correct or not. Usually checked with the original copy.
  2. Double-Entry
    1. The data is entered twice. The computer compares the data, and anything that doesn't match is questioned.
2. Data Validation - it is to check the data input is incomplete or unreasonable
  1. Presence- Check
    1. It is a check to see if the data is entered.
      1. E.G: You forgetting to type ponylover43@yahoo.com.sg in the E-mail section. Then there is a warning that says you need to type it in.
  2. Format-Check
    1. It checks whether the data is in the correct format.
      1. E..G:date should be in DD/MM/YYYY (Not like USA)
  3. Check-Digit
    1. Used for numerical data. An extra digit is added to a number which is calculated from the digits. The computer checks this calculation when data are entered
  4. Character-Type Check
    1. Character type check is a check to make sure only certain types of characters are in the data.
      1. E.G: A name should not have numbers.
  5. Range-Check
    1. A range check is a check to make sure a number is within a certain range.
      1. E.G: A driver's age should be 17 to 99.
  6. Parity check
    1. Use the last digit of a set of data to check the correctness of data. In a set of data,, the last digit is used as parity digit. If there are even number of 1 in this set of data, the parity digit is set to 0. If there are odd number of 1 in this set of data, the parity digit is set to 1.
Data Process
1. Batch Processing
  1. Batch processing is where the data is collected first, and then at a certain period of time, usually after a month, the data will be updated.
    1. Adv - The data can be processed at a later time so that the resources can be used to perform other tasks
2. Real-time Process
  1. Real-time Processing is where the data is collected and updated on the spot.
    1. Adv - the data will be updated immediately
Data Collection
1. Open-Loop
  1. The sensor detects a change in value. Then, it will send a signal to the ADC, which will convert the signal from analog to digital for the computer to interpret. Then it will send a signal to the computer. The computer will display the signal, showing that there is a change in the value.
    1. Sensor
      1. Analog to Digital Converter(ADC)
        Computer
2. Close Loop
  1. The sensor detects a difference in the system. Then, it will send a signal to the ADC, which will convert the signal from analog to digital for the computer to interpret. Then, it will send a signal to the computer. The computer will compare the original value with the current value. Then, it will send a signal to the DAC, which converts the signal from digital to analog. Then, it will send a signal to the actuator which will change the current value to its original value.
    1. Sensor
      1. Analog To Digital Converter(ADC)
        Computer
        Digital To Analog Converter(DAC)
        Actuator
        Sensor
Data Transfer
1. Network Topology (for sharing of resources and easy communication with each other)
  1. Star
    1. Adv - Easy to modify (add or reduce no of computer)
    2. Disadv - More expensive because all computers need to link to a central location using cables
  2. Ring
    1. Adv - Reduce chances of collision of data
    2. Disadv - If one computer fails, the whole network is affected
  3. Bus
    2. Adv - Simple and easy to set up
    3. Disadv - Heavy traffic can slow down the network because all computers shares the main line

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	Created by Haha_fizul over 8 years ago

	Copied by chong.lee.soong over 8 years ago