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Glossary
PG / programming device
A PG is a personal computer designed specifically for use in industry. A PG is fully equipped
for programming SIMATIC automation systems.
PG Routing
Using PG routing, it is possible to access programmable modules or modules with diagnostic
capability beyond network boundaries from a programming device (PG) or computer (PC).
Polling
In polling mode, data exchange is controlled by the master station. This polls the connected
stations (including node stations) one after the other. Stations with data to transmit send it as
soon as they are polled. Stations that do not currently have any data only acknowledge the
poll. Data from the master station to the stations can be transferred at any time between
individual polls.
Polling mode
Polling
→
Polling with time slots
The polling with time slots mode is used in a wireless network in which the use of the radio
frequency assigned by the registration authorities must be shared with other users. Each
user typically has 6 seconds per minute to exchange data with its stations. The frequency
must then be released for other operators. During the allocated time slot, this pooling variant
functions like a normal polling system.
PROFIBUS
PROFIBUS is the open, internationally standardized (EN50170) bus system for process and
field communication with field devices and for data communication within an automation cell.
The uses of PROFIBUS range from production and process automation to building
automation.
Protocol
A protocol is a set of rules for controlled transfer of data. Protocols, for example, specify the
data structure, the structure of data packets and the coding. Protocols can also specify a
control mechanisms and hardware and software requirements.
Requested message
Requested messages are practically identical to data messages. However, they contain a
special ID that indicates that they are not normal spontaneous data messages and that they
are transferred due to a request from the master. These data messages are then sent when
a station or node TIM has received the organizational message for a general request from
the master station.
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SINAUT ST7 Station control system - System Manual
System Manual, 05/2007, C79000-G8976-C178-06
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