You may see an uptick in SCADA/ICS related posts since I’ve been studying and preparing for the SANS GICSP (Global Industrial Cyber Security Professional) certification. It’s a lot of interesting material and just wanted to share a little about industrial control system field components.
Field Components
PLC (Programmable Logic Controller) is a computer-based solid-date device that controls industrial equipment and processes.
RTU (Remote Terminal Unit) is used to report local system information and communicate with the upstream supervisory system.
PLC vs RTU
- Both have an array of input/output connections and software/logic for operations input/output for automation and safety
- RTU’s are generally less capable than PLCs
- RTU’s are more suitable for large geographical areas. They utilize wireless communications to communicate back to the supervisory system.
- PLCs are generally suited for a local control system that resides entirely at once local and uses physical media for communications.
- The lines between the two are blurring more recently though
DPR (Digital Protective Relay) are single purpose microcontrollers to detect faults in a system and often report to an RTU. DPRs measure voltages and currents.
IED (Intelligent End Device), a DPR is an example of an IED.
PMU (Phasor Measurement Unit) is a device that measures that electrical waves on an electricity grid using a common time source for synchronization.
RTOS (Real Time Operating Systems)
- Process input in real time
- Examples
- QNX
- VxWorks
- Windows CE
- QNX
- Microkernel OS (only does three things – CPU scheduling, interrupts, and interprocess communication)
- Runs on MIPS, PowerPC, Arm, x86
- VxWorks
- Memory separated kernel (kernel and user-space processes have isolated memory segments)
- Commonly found to have debug tools still installed on production systems. Can be used for forensic analysis or attacks.
- Windows CE
- Much smaller kernel
- Visual Studio for development/debugging
- Runs on multiple architectures
- Sometimes offers internet explorer even
Sensor Networks are spatially distributed and monitor environmental qualities like temperature, humidity, vibration, sound, and air pressure.
Other Fields Devices
- Valves, solenoids, pumps, agitators, burners, compressors, etc.
- Wiring ties the devices to the things
- Basic communication is referred to as “I/O” (Input/Output)
Digital I/O is an input or output where the specified value is communication as simple on/off signals.
Analog I/O is an input or output where the specified value is communicated by varying the voltage or current of a signal.
A setpoint is the desired process output that an automatic control system will aim to reach. An example is a boiler might have a temperature setpoint that the control system aims to attain.
SIS (Safety Instrumented System) detect and remediate unsafe situations.
Sources:
- SANS GICSP Course Materials
- PLC – http://www.windtechautomation.com/
- RTU – http://www.energy.siemens.com/