Characteristics of a data logger

A data logger is an instrument that automatically measures and records data from sensors against time, usually in non-volatile memory, for later transfer and analysis; it may operate unattended and stand-alone.

Characteristics of a data logger

1. Number of channels: from one to hundreds of analog and digital inputs, with a multiplexer.
2. Input types and range: thermocouple, RTD, voltage (mV to 10 V), current (4-20 mA), pulse; programmable gain.
3. Resolution and accuracy: ADC of 12-24 bits; accuracy depends on the signal conditioner and the ADC.
4. Sampling rate: programmable from a sample per day to thousands of samples per second; scan rate per channel.
5. Memory capacity: non-volatile flash, SD card; number of records and circular/linear logging.
6. Real-time clock: time stamping of data with accuracy and battery backup.
7. Power: low power, battery operated, mains with backup; long life.
8. Communication: USB, RS-232/485, Ethernet, wireless (Bluetooth, GSM) for download and remote access.
9. Alarms and display: limit alarms, status LEDs, LCD.
10. Software: setup, graphing, analysis and export (CSV).
11. Ruggedness and size: environmental protection (IP rating), temperature range, portable or compact.
12. Trigger modes: start/stop by time, level or event; programmable.
13. Isolation and noise rejection between channels and from ground.