The main advantage of a PLC over a conventional relay circuit is:

• Slower response times compared to a relay circuit
• More relay contacts are available

• More flexibility, easier troubleshooting, faster response times, and can handle more complex logic.
• Limited to simple logic operations

An example of a electronic control input sensor is:

• Limit Switch

• Indicator Lamp

• Float Switch

• Proximity Switch

The supply for devices connected to the outputs of a programmable controller

• comes from within the PLC

• is always DC

• comes from an external source

• is always AC

The supply for devices connected to the inputs of a programmable controller

• comes from within the PLC and is always DC

• comes from within the PLC and is always AC

• comes from an external source and is always DC

• comes from an external source and is always AC

If four inputs are logic 1 at the same time for the Hitachi EH-A-14DR the current drawn from the power supply would be:

• 7.5 mA

• 15 mA

• 30 mA

• 350 mA

This symbol in a ladder diagram represents:

• capacitor

• 2. normal contact

• 2. non polarised capacitor

• 2. inverted contact

What is the primary function of a PLC's CPU?

• To execute control instructions contained in the program memory

• To supply power to the input and output devices

• To convert AC power supply to DC power supply

• To provide a physical interface for programming the PLC

Which of the following is a common feature of PLCs that makes them suitable for harsh industrial environments?

• High sensitivity to electrical noise

• Ability to operate in a wide range of temperatures

• Requirement for frequent maintenance

• Use of fragile components similar to those found in consumer electronics

How does a PLC communicate with other industrial automation equipment?

• Through wireless connections only

• By using dedicated control cables

• Through industrial networks and communication protocols such as Ethernet/IP, Profibus, or Modbus

• PLCs do not communicate with other devices

The program downloaded to the PLC is permanently stored in what type of memory?

• EEPROM

• RAM

• ROM

• Brain