PERA Level 0 & 1 Technology Overview and Compromise GICSP Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   Which of the following is a common analog signal type used to transmit a sensor value from a Level 0 device to a Level 1 controller?

   • A4-20 mA current loop
   • BModbus TCP frame
   • CRS-232 serial communication
   • DEtherNet/IP packet
   Reveal Solution Discussion Select an answer first
2. 22foundation · easy

   What is the primary role of a PLC at Level 1 of the Purdue model?

   • ATo provide a graphical interface for operators to monitor the process.
   • BTo execute control logic and send output signals to actuators based on input from sensors.
   • CTo store historical process data for long-term analysis.
   • DTo route network traffic between the control network and the enterprise network.
   Reveal Solution Discussion Select an answer first
4. 23foundation · easy

   What is a potential physical impact of an attacker compromising a Level 0 actuator, such as a control valve?

   • AThe valve could be forced to a fully open or closed position, causing process upsets or equipment damage.
   • BThe attacker could alter the HMI display to show false readings.
   • CThe attacker could encrypt the plant's data historian.
   • DThe attacker could steal sensitive corporate financial data.
   Reveal Solution Discussion Select an answer first
5. 24application · medium

   A food processing plant has a PLC that controls a filling machine. The PLC uses a load cell (Level 0) to measure the weight of a container and controls a filling valve. The load cell is connected to a weight transmitter that outputs a 4-20 mA signal. The PLC's analog input module is configured for 4-20 mA. The plant has noticed that the fill weights are inconsistent. Which of the following is the most likely cause?

   • AThe filling valve is not closing quickly enough.
   • BThe weight transmitter's 4-20 mA output is not linear.
   • CThe PLC's analog input module is not calibrated.
   • DThe load cell is not calibrated correctly.
   Reveal Solution Discussion Select an answer first
6. 25application · medium

   A manufacturing plant has a PLC that controls a robotic arm. The PLC receives a signal from a limit switch (Level 0) to detect the arm's position. The limit switch is a 2-wire AC sensor. The PLC input module is a 24 VDC sinking input. Which of the following is the correct way to interface the limit switch with the PLC?

   • AReplace the limit switch with a 24 VDC sensor.
   • BUse a relay to interface the AC limit switch with the DC PLC input.
   • CConnect the limit switch to a 24 VDC power supply and then to the PLC input.
   • DConnect the limit switch directly to the PLC input module.
   Reveal Solution Discussion Select an answer first