Data loggers acquire digital data from sensors and other signals. They are primarily used to store data for subsequent downloads to a host PC, but may also include real-time features such as monitors and alarms. Important specifications to consider when searching for data loggers and data recorders include:

• differential analog input channels
• digital I/O channels
• sampling frequency
• resolution and accuracy

Differential channels use the difference between two signals as an input, common mode is filtered out. In some systems, differential inputs are combinations of two single-ended inputs; in this case, twice the number of differential channels would be available as single-ended inputs.
Digital or discrete channels are used for low-level on-off signals used in applications such as communication, user interface, or control. Sampling frequency is the frequency of the analog signal sampling and conversion to a digital value.
Resolution refers to the degree of fineness of the digital word representing the analog value. Data loggers accuracy depends on the signal conditioning linearity, hysteresis, temperature considerations, etc.

• IC or board mount
• circuit board
• panel or chassis mount
• modular bay or slot system
• rack mount
• DIN rail and stand-alone

• general lab or industrial
• environmental
• vehicular
• marine
• aerospace or military

• DC voltage
• DC current
• AC voltage
• AC current
• frequency and charge

• accelerometer
• thermocouple
• thermistor
• RTD
• strain gauge or bridge
• LVDT or RVDT

• encoder
• counter or tachometer
• timer or clock
• relay or switch

Transducers and excitation are also important to consider when searching for data acquisition. Many data loggers have integral sensors or transducers. These sensors can have voltage or current excitation. Common outputs for data acquisition products include:

• voltage output
• current output
• frequency output
• timer or counter output
• relay output
• resistance or potentiometer output

Considering the user interfaces available is important when searching for data loggers. User interfaces available include no display, front panel and display, touch screens, hand-held or remote programmers, and computer programmable. Host connection choices include direct backplane interface, RS232, RS422, ST485, USB, IEEE 1394, GPIB, SCSI, TTL, parallel, Ethernet, modem, and radio or telemetry. The transmission rate of data is important to consider. Many data loggers are web enabled for web addressing. Additional specifications to consider when searching for data acquisition systems and instruments include application software, memory and storage, network specifications, and environmental parameters.

ETS are able to offer the latest in data loggers, please contact us for more technical information on the products that we offer.