Glossary
TIM 1531 IRC
326
Operating Instructions, 02/2018, C79000-G8976-C468-02
Context: TeleControl
Image memory / send buffer principle
●
Image memory principle
A fixed position is reserved in the image memory for each data message transferred to
the TIM for transmission. Each newly transferred message always overwrites the old
message in the image memory.
If a send message is entered using the image memory principle, only a reference to the
location of the message in the message image memory is entered. If the TIM has not yet
been able to transmit the message when the same message is transferred to it again, the
message is not entered in the send buffer a second time, but rather the image is simply
updated.
At the time of transmission, the message is sent with its up-to-date content from the
image memory. Only then can the message be entered in the send buffer again.
Transmission using the image memory principle achieves the following:
–
There is less load on transmission link, fewer messages are transmitted.
–
There is less load on the send buffer of the TIM; an image memory message is
entered a maximum of once in the send buffer.
●
Send buffer principle
If a data frame is transmitted using the send buffer principle, it is entered completely in
the send buffer each time it is transferred to the TIM. If such a message cannot or should
not be transmitted immediately, it may exist more than once in the send buffer.
When it is sent, the message is taken completely from the send buffer and transmitted.
Inter-station communication
Communication between two stations, which is mediated by a Telecontrol/SINAUT master
station.
For dial-up networks, a direct connection between the two stations is established in ST7
networks.
See also "Direct communication".
IRC
Industrial Remote Communication
SIMATIC NET product group for telecontrol.
ISDN
Integrated Services Digital Network
Standard for a digital transmission network for telephone, telefax, telex, teletext and datex-
J/L/P services. The data of various services can be transferred simultaneously. Telephone
connections normally operate at transmission speeds of 56 to 64 Kbps.
