What is data logger? how they are used in Railway Signalling System?

Question

What is data logger? how they are used in Railway Signalling System?

Answer 1

http://www.madgetech.com/pdf_files/app_n...

Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment only. It is common for general purpose types to be programmable however many remain as static machines with only a limited number of changeable parameters. Electronic dataloggers have replaced chart recorders in many applications.

A data is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered and portable.