MBI block diagram and advantages in industry

Block diagram of an MBI system

Sensor -> Signal conditioner -> S/H -> ADC --+
  ^                                          v
  |                                +------------------+
PLANT                              | Microprocessor   |<-> ROM/RAM
  |                                | (CPU, I/O ports) |<-> Keypad,
  v                                +------------------+    Display,
Actuator <- Driver <- DAC <----------------+  |           Printer,
                                              +-> Serial link

• Sensor/transducer: converts temperature, pressure, level or flow to an electrical signal.
• Signal conditioning: amplification, filtering, isolation and scaling.
• S/H + ADC: digitises each channel; a multiplexer shares the ADC among channels.
• Microprocessor, ROM, RAM: runs the monitoring and control program and stores data.
• I/O ports: keypad for set points, display, printer, alarm outputs.
• DAC, driver, actuator: operate valves, motors and heaters.
• Communication interface: reports to SCADA or a host PC.

Advantages in industrial plants for control and automation

1. Automatic closed-loop control (PID) keeps process variables at the set point, improving product quality.
2. A single unit supervises many loops, reducing instrument cost and panel space.
3. Fast detection of abnormal conditions with alarms and safe shutdown.
4. High accuracy and repeatability through digital processing and calibration.
5. Flexibility: a changed process needs only a program change.
6. Data logging, trend display and remote monitoring help maintenance and planning.
7. Reduced manpower, lower energy use and less wastage.
8. Self-diagnosis reduces downtime.