29.4 PRACTICE PROBLEMS

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1. Write a program that will input an analog voltage, do the calculation below, and output an analog voltage.

2. The following calculation will be made when input `A' is true. If the result `x' is between 1 and 10 then the output `B' will be turned on. The value of `x' will be output as an analog voltage. Create a ladder logic program to perform these tasks.

3. You are developing a controller for a game that measures hand strength. To do this a `START' button is pushed, 3 seconds later a `LIGHT' is turned on for one second to let the user know when to start squeezing. The analog value is read at 0.3s after the light is on. The value is converted to a force `F' with the equation below. The force is displayed by converting it to BCD and writing it to an output card (O:001). If the value exceeds 100 then a `BIG_LIGHT' and `SIREN' are turned on for 5sec. Use a structured design technique to develop ladder logic.

4. 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

5. You need to read an analog voltage that has a range of -10V to 10V to a precision of 0.1V. What resolution of A/D converter is needed?

6.