The computer link RK 512 controls controls data transfer via a bidirectional point-to-point connection between the local controller and a communication partner.
Here, the RK 512 protocol uses the transport layer known from the ISO-OSI reference model, layer 4. This provides a very high level of transfer security. Services used with RK 512 are acknowledged.
||In the case of a SEND/PUT message, the local station sends a command message with user data to the communication partner which in turn answers with a response message.|
||In the case of a GET message, the local station sends a command message without user data and the communication partner answers with a response message with user data.|
Advantages of the protocol:
- Can be used well with third-party systems.
- Suitable only for medium data volumes (<= 1024 bytes)
- Acknowledged data transfer
- Possible to read/write separately definable data areas
Disadvantages of the protocol:
- Not very good performance due among other things to use of procedure 3964R
- RS 485 cannot be used as bus medium
|Data area per job
||Up to 1024 bytes per message|
(128 bytes per segment)
||Layer 4 of the ISO-OSI reference model|
(technically speaking, the connection works on layer 7)
|Number of possible connections per CP
||1 per interface (point-to-point)|
General information on communication via SIMATIC S7 and a detailed description of the RK 512 protocol are available in Entry ID: 20982954.
RK 512, Point-to-point, Serial connection, Third-party system