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If the
Solution:
22.5 SUMMARY
* A/D conversion will convert a continuous value to an integer value.
* D/A conversion is easier and faster and will convert a digital value to an analog value.
* Resolution limits the accuracy of A/D and D/A converters.
* Sampling too slowly will alias the real signal.
* Analog inputs are sensitive to noise.
* The analog I/O cards are configured with a few words of memory.
* BTW and BTR functions are needed to communicate with the analog I/O cards.
plc analog -22.23
• Analog shielding should be used to improve the quality of electrical signals.
22.6 PRACTICE PROBLEMS
1. Analog inputs require: a) A Digital to Analog conversion at the PLC input interface module b) Analog to Digital conversion at the PLC input interface module c) No conversion is required d) None of the above
2. You need to read an analog voltage that has a range of -10V to 10V to a precision of +/-0.05V. What resolution of A/D converter is needed?
3. We are given a 12 bit analog input with a range of -10V to 10V. If we put in 2.735V, what will the integer value be after the A/D conversion? What is the error? What voltage can we calculate?
4. Use manuals on the web for an analog input card, and describe the process that would be needed to set up the card to read an input voltage between -2V and 7V. This description should include jumper settings, configuration memory and ladder logic.
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