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08.89
The following data transfer services are to be added to the above system aspects of the
protocol:
•
Identification of the communication relation of an AP application
•
Multiplexing at layer 7, i.e. a multiple use of lower-level resources, in this case a layer 4
link.
•
Efficient job management with independent, configurable error correction measures.
•
Standardization of the technological functions, i.e. standardization of "what" one node
requests from the other node.
•
SINEC AP is a protocol between AP applications, i.e. reliable data transfer ensured by a
user acknowledgement is also a service.
•
Segmenting, i.e. division of useful data into units which can be transmitted by the
communication system and which can be managed by the AP applications as a unit.
•
Transmission of information on error states in the communication system at layers 5 to 7.
•
Modular, hierarchical structure (syntax) of the protocol, i.e. extendibility is ensured and
simple implementation is possible.
The AP1 header is 22 bytes long (see figure "SINEC AP1 header (system part)") and it can be
split up into the following protocol element groups:
•
Function-oriented protocol elements
They determine the meaning of the message contents.
•
Control elements
These control the sequences and provide information on the session elements.
•
Management elements
These provide information for the administration of AP applications.
•
Identification elements
By means of these elements, a communication relation on AP application level is
identified in the protocol.
•
Size information
They contain information on the data structure of the AP PDU.
The system part is the crucial part of the message. It transports in the protocol elements the
codes which can be interpreted by the receiver or by the communication system.
For further specifications on SINEC AP, please refer to the "SINEC AP manual"
(Order no: 6 GK 1972-7AA02-0AA0).
© Siemens AG 1989 All Rights Reserved
SINUMERIK 840/880 (PJ)
6FC5 197-0AB20-0BP0
3 Interface Modules
3.4.1 SINEC AP 1 protocol
3–29
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