I/O tags are objects of the D2000 system, which reflect the values of particular measured and monitored tags in real technology. According to the relation to the real environment, they are divided into input and output ones; and according to the character of parameters they represent, they are divided into analog, integer, digital, quaternary, and time (absolute and relative) ones.

Acquiring values of I/O tags defined in the system is performed by the communication process - D2000 KOM - by means of the communication with autonomous control systems, interface units, or communication computers, which mediate this information. The D2000 KOM process obtains raw values of defined I/O tags, transforms them to defined technical units, provides input filtering and verification of values. It reports changes in the defined tags' values to the D2000 Server.

Object hierarchy  - Communication process, Line, Station, IO tag