Siemens SINAUT ST7 System Manual page 280

Glossary
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
possible. It is possible to have several node stations in a SINAUT network; in other words
the data traffic between stations and master station can involve two or more node stations.
Node station TIM
WAN interface of a TIM in a node station set to the "node station" function.
If the TIM used in a node station has two WAN interfaces, the "station", "node station" and
"master station" functions can be used in any combination on one TIM.
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System Manual, 07/2009, C79000-G8976-C178-07
Station control system