The DL3 Data Logger from Fieldpiece Instruments measures and records any parameter from any accessory head Instrument we offer. It holds up to 20,000 data points and can be set to record in a range from once every second to once every 999 hours. Record and export data in .xls format to your PC for use in work orders, troubleshooting and service contracts. A real-time clock time stamps every data point for pinpoint accuracy. Use multiple data loggers to monitor several parameters to make troubleshooting and commissioning easier. We've updated the function of the DL3 to include features you asked us to add. Combined with our accessory head instruments, we're comfortable saying the DL3 is the most versatile data logger for HVAC/R field service.