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Data logger block diagram and operation

Short answer

A data logger automatically measures and records sensor signals over time. It consists of sensors, signal conditioning, a multiplexer, sample-and-hold, ADC, a controller with real-time clock, memory, display, and communication interface.

What is a data logger? Draw its block diagram and explain the operation of each block.

A data logger is an electronic instrument that automatically measures and records one or more physical quantities (temperature, pressure, voltage, etc.) with time, usually in internal memory, for later retrieval and analysis. It may work unattended for a long period.

Block diagram

 Sensors -> Signal  -> Input   -> S/H -> ADC --+
 (1..n)     conditioner scanner(MUX)           v
                                      +--------------+
 Real time clock ---------------------| Controller / |-> Display
 Keypad (setup) ----------------------| Microprocessor|-> Alarm/Output
                                      +------+-------+
                                             |   |
                                    Memory (storage)  Communication
                                                      (USB/RS-232/BT)
 Power supply (battery/mains) feeds all blocks

Operation of the blocks

  1. Sensors/transducers: convert physical quantities into electrical signals.
  2. Signal conditioner: amplifies, filters, linearises and level shifts the signals to the ADC range; also isolation and cold-junction compensation.
  3. Input scanner (multiplexer): connects the channels one by one to the ADC, in a programmed sequence and rate.
  4. Sample and hold: holds the signal constant during conversion.
  5. ADC: converts the analog value into digital words.
  6. Controller (microprocessor/microcontroller): controls scanning and timing, processes data (scaling, limit checking), time-stamps it, and manages memory and communication.
  7. Real-time clock: supplies date and time for each sample.
  8. Memory/storage: RAM, flash or memory card stores the data for later transfer.
  9. Display and keypad: show readings and set sampling rate, channels, alarm limits.
  10. Communication interface: transfers data to a PC (USB, RS-232, Ethernet, Bluetooth).
  11. Power supply: mains or battery with backup so that no data is lost.

✓ Answer checked by Claude Sonnet 5.5

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