Technical data

Glossary
Software
System Manual, 07/2009, C79000-G8976-C222-07
449
Data manager
The accrued data is managed by the data manager in WinCC. The data manager works with
data created in the WinCC project and data stored in the project database. It handles the
entire management of WinCC tags while WinCC is in runtime mode. All WinCC applications
request the data from the data manager in the form of WinCC tags. These applications
include Graphics Runtime, Alarm Logging Runtime and Tag Logging Runtime.
To allow WinCC to communicate with the widest variety of data sources (programmable
controllers, ST7cc servers etc.), various communications drivers are used.
A communications driver is a C++ DLL that communicates with the data manager over a
specified interface known as the channel API. The WinCC tags are supplied with process
values over the communications driver.
Data messages
The actual transmission of data takes the form of data messages. These contain a fixed
amount of a specific information type.
There are status messages, analog value messages, counted value messages, command
messages, setpoint messages, parameter messages and data messages for the various
information types.
DCF77 radio clock
DCF77 is a time signal transmitted on the normal frequency 77.5 kHz as encoded time
information. Reception of the time signal is restricted to Western Europe.
Some TIM variants (TIM 4VD, TIM 42D, TIM 43D, TIM 44D, TIM 4RD) are equipped with a
DCF77 receiver module that can receive the DCF77 time signal either over an indoor or
outdoor antenna. The ST7 time management currently requires the existence of a DCF77
time signal to allow time synchronization of the stations and the control center throughout a
network.
For applications that cannot receive the DCF77 time signal, SINAUT provides a GPS
receiver module with a GPS outdoor antenna that converts the GPS Time signal for the
DCF77 receiver module.
Direct data communication
Communication between two stations. In dial-up networks or in Ethernet, this is achieved by
direct connection establishment between the two stations. On dedicated lines and in wireless
networks or in GPRS mobile wireless service or when using the MSC protocol, direct
communication is more "indirect". It is switched via the closest → master TIM.
DNS
Domain Name System, a distributed database that manages the name space in the Internet
DSL
Digital Subscriber Line