EET 204 Mid Mod Exam Ch 1-6, 2012
Multiple Choice
Identify the one choice that best completes the statement or answers the question and place your answer in the space provided..
____ 1. The power required to operate the logic circuits
of the processor unit is typically:
a. / low voltage ac. / c. / high voltage ac.b. / high voltage dc. / d. / low voltage dc.
____ 2. The basic rule for an AND gate is:
a. / if all inputs are 1, the output will be 1.b. / if all inputs are 1, the output will be 0.
c. / if all inputs are 0, the output will be 1.
d. / both a and b.
____ 3. Programmed latching circuits are retentive. This means that if power is interrupted the output will ____ when power is returned,
a. / switch to the ON state.b. / switch to the OFF state.
c. / remain in its original ON or OFF state.
d. / flash ON and OFF.
____ 4. The PLC program shown is a ___ type.
a. / Functional Block Diagram / c. / Structured Textb. / Structured Text / d. / Ladder Diagram
____ 5. A human machine interface (HMI)
a. / allows the user to monitor a process.b. / allows the user to control a process.
c. / can provide a graphical representation of a process .
d. / all of the above.
____ 6. Branch input instructions are used to create a:
a. / parallel connection of input modulesb. / series path of input instructions.
c. / serial connection of input modules
d. / parallel path of input instructions.
____ 7. A gate is a device that:
a. / changes alternating current to direct current.b. / performs a logical decision based on its outputs.
c. / performs a logical decision based on its inputs.
d. / allows current flow in one direction only.
____ 8. The symbol shown is that for a:
a. / heater. / c. / motor.b. / horn. / d. / solenoid.
____ 9. Which of the following is not an advantage that PLCs
offer over the conventional relay-type of control system?
a. / More reliable / c. / Smaller sizeb. / Less expensive / d. / Higher current capacity
____ 10. A programmed XIO instruction:
a. / is examined for an ON condition.b. / is examined for an OFF condition.
c. / with a bit status of 1 will not have logic continuity.
d. / both a and b.
____ 11. The acronym BCD stands for:
a. / binary-coded decimal. / c. / base code decoder.b. / base-coded decimal. / d. / binary code decoder.
____ 12. An actuator is a device that:
a. / changes DC to ACb. / changes AC to DC
c. / converts mechanical movement into an electrical signal
d. / converts an electrical signal into mechanical movement
____ 13. In the sign bit position, a 1 indicates a(n):
a. / octal code. / c. / hexadecimal code.b. / positive number. / d. / negative number.
____ 14. In ladder logic programs, outputs are represented by:
a. / either a or b.b. / coil symbols.
c. / schematic load device symbols.
d. / contact symbols.
____ 15. The NOT function can be thought of as:
a. / a FALSE-to-TRUE converter. / c. / an inverter.b. / a changer of states. / d. / all of these.
____ 16. The sensor illustrated is a:
a. / strain gauge load cell / c. / turbine flow meterb. / retroreflective sensor / d. / thermocouple
____ 17. A(n) ___ operates by sending sound waves toward a target and measuring the time it takes for the pulses to bounce back.
a. / bar code scanner / c. / flowmeterb. / ultrasonic sensor / d. / pressure sensor
____ 18. The electromagnetic latching relay:
a. / is used to lock in a conditionb. / uses a latch coil to set and hold the relay in the latched position.
c. / uses an unlatch coil to disengage the mechanical latch.
d. / all of these.
____ 19. The status bit of switches and pushbuttons connected to a PLC are stored in the:
a. / output image table file. / c. / input image table file.b. / user program. / d. / all of these.
____ 20. The Boolean equation for the logic represented in the ladder diagram can be expressed as:
a. / Y = (AB) + (ACD) + (DE) + (BCE)b. / Y = (AB) + (AC) + (AD) + (ED)
c. / Y = (AB) + (ACD) + (DE)
d. / Y= (AB) + (CD) + E
____ 21. The ____ instructions always interpret a 1 status as true and a 0 status as false.
a. / XIO / c. / contactb. / XIC / d. / all of these
____ 22. The output data is sent to the
a. / output field devices. / c. / ladder program.b. / output module. / d. / input module.
____ 23. The decimal system has as its base:
a. / 2. / c. / 8.b. / 10. / d. / 5.
____ 24. An encoder is used to:
a. / convert motion into a digital signalb. / change DC to AC
c. / encode signals from a scanner
d. / decode signals from a scanner
____ 25. Basically, the function of a PLC is to:
a. / make logical decisions and control outputs based on them.b. / control the speed of motors.
c. / control a high voltage output with a low voltage input.
d. / amplify various weak signal sources.
____ 26. A normally open limit switch is wired to an input module, and programmed using XIO instruction. The instruction will be true when:
a. / the limit switch is openb. / never
c. / power is applied and the PLC is in the run mode
d. / the limit switch is closed
____ 27. Capacitor proximity sensors:
a. / are actuated by both conductive and nonconductive materials.b. / have a long sensing range.
c. / produce an electromagnetic field
d. / are actuated by conductive materials only
____ 28. When a field device contact connected to the input module closes:
a. / a logic 0 is recorded in the memory location of the coil with the same address.b. / a logic 1 is recorded in the memory location of the coil with the same address.
c. / a logic 1 is recorded in the memory location of the contact with the same address.
d. / a logic 1 is recorded in the memory location of the contact with the same address.
____ 29. The output interface module connects to:
a. / sensing devices such as switches or pushbuttons.b. / load devices such as lamps or solenoids.
c. / a programming device such as a computer.
d. / all of the above.