CPT Computer Systems & Software Updates 3 — Questions and Answers
Question 1: Which of the following best describes a 'hot standby' redundancy configuration in a process control computer system?
- A spare controller stored in a warehouse for emergencies
- A secondary system running in parallel that takes over instantly on primary failure (Correct answer)
- A backup system that requires manual activation after a fault
- A read-only mirror used only for data logging
Correct answer: A secondary system running in parallel that takes over instantly on primary failure
Hot standby means the secondary system is live and synchronized so it can assume control immediately without operator intervention.
Question 2: In industrial cybersecurity, what is an 'air gap'?
- A physical space required between control panels for ventilation
- Physical or logical isolation of a control network from external networks (Correct answer)
- A gap in firewall rules allowing specific traffic
- The delay between sensor reading and controller response
Correct answer: Physical or logical isolation of a control network from external networks
An air gap isolates the OT network from the internet or corporate IT network to prevent cyber intrusions.
Question 3: What is the primary function of an OPC server in a process plant?
- To provide wireless connectivity for mobile devices on the plant floor
- To act as a standardized middleware that allows different software applications to share process data (Correct answer)
- To control valve positions directly based on PID output
- To archive safety instrumented system (SIS) trip logs
Correct answer: To act as a standardized middleware that allows different software applications to share process data
OPC (OLE for Process Control) servers provide a standard data-sharing interface between controllers, historians, and HMI applications from different vendors.
Question 4: Which maintenance strategy schedules software updates based on elapsed time or usage cycles rather than detected faults?
- Corrective maintenance
- Predictive maintenance
- Preventive maintenance (Correct answer)
- Reactive maintenance
Correct answer: Preventive maintenance
Preventive maintenance applies updates on a fixed schedule to reduce failure risk before problems occur.
Question 5: A process plant's control system logs show repeated 'memory overflow' errors on a workstation. What is the most likely corrective action?
- Recalibrate the field transmitters connected to that workstation
- Upgrade RAM or optimize/patch the software causing excessive memory use (Correct answer)
- Replace the workstation's network interface card
- Adjust the PID tuning parameters on the associated controller
Correct answer: Upgrade RAM or optimize/patch the software causing excessive memory use
Memory overflow errors indicate the application is consuming more RAM than available, requiring a hardware upgrade or software patch.
Question 6: What is the purpose of a Management of Change (MOC) process when updating control system software?
- To notify vendors of required software customizations
- To formally evaluate, approve, document, and communicate the risks of the change before implementation (Correct answer)
- To automatically deploy updates across all plant nodes
- To generate purchase orders for new software licenses
Correct answer: To formally evaluate, approve, document, and communicate the risks of the change before implementation
MOC ensures that software changes are assessed for safety and operational impacts and are properly authorized before being made.
Question 7: Which file type is typically used to store DCS controller configuration backups that can be restored after a hardware failure?
- .mp4
- .cfg or .bak (vendor-specific configuration files) (Correct answer)
- .exe
- .log
Correct answer: .cfg or .bak (vendor-specific configuration files)
DCS vendors use proprietary configuration file formats (often .cfg, .bak, or similar) that store all controller logic and parameters for restoration.
CPT Computer Systems & Software Updates 3
Which of the following best describes a 'hot standby' redundancy configuration in a process control computer system?