Technical data

Glossary
Software
System Manual, 07/2009, C79000-G8976-C222-07
453
LTOP
(Line Transformer with Overvoltage Protection)
Copper dedicated lines are highly susceptible to electromagnetic interference. The coupling
of extraneous voltages can be inductive or capacitive, for example due to the effects of
lightning. Direct conductive coupling is also possible due to bad insulation.
The LTOP overvoltage protection modules limit extraneous voltage and overvoltage to a
non-critical level. The floating transformer also provides electrical isolation preventing
coupling of voltages into other cable sections. An LTOP protects persons and investment
and is therefore an indispensable safety element in private dedicated line networks.
Main and subcycle
The sequence of the polling cycle can be structured on the master TIM by assigning
individual polling stations to a main cycle or a subcycle. The subcycle is always activated at
the end of the main cycle; in other words, once all stations from the main cycle have been
polled, a certain, selectable number of stations are polled in the subcycle. Following this, all
the stations in the main cycle are polled again.
Master TIM
WAN interface of a TIM set to the "master" function. Use in control centers and node
stations.
MPI
The multipoint interface (MPI) is the programming device interface of SIMATIC S7. Devices
with an MPI interface (for example a TIM), can also communicate with each other (MPI bus).
MSC protocol
The MSC protocol is a proprietary protocol and is used in SINAUT ST7 for the data
exchange between TCP/IP-compliant devices in Ethernet, landline or mobile wireless
networks. The MSC protocol provides an authentication mechanism and simple encryption of
data. To transfer messages in IP-based WANs, the MSC protocol is linked into the protocol
of SINAUT ST7.
Multimaster polling with time slots
When stations need to communicate with more than one master station in dedicated line or
wireless operation, the multimaster polling with time slots mode is used. Each of the
connected master stations is assigned one or more defined time slots per minute for polling.
The master stations then have their turn to poll in every minute.
Node station
A node station is a station located between the master station and stations in the hierarchy
of a telecontrol network. One or more subordinate stations are connected to a node station.
The data traffic between these stations and the master station is handled via the node
station. Direct data exchange between the node station and the subordinate stations is also