Siemens SIMATIC S5 Manual page 197

S5-95U, SINEC L2
B SAP Numbers / Job Numbers
This appendix contains information that you do not have to know to work with the S5-95U
programmable controllers as SINEC L2 stations. This appendix is for the network expert who wants
more details about the internal process of data transfer.
Definition of terms:
The job number carried by a frame running on the network helps the required station to identify and
read in the frame. To achieve this, another parameter is provided, the SAP (Service Access Point).
A mail carrier transporting a package to the receiver is in a situation similar to the message on the
bus:
• The residence number (destination address) has to be identified.
• The correct residence door (=SAP) must be found in order to deliver the package (message).
The system automatically assigns the SAP numbers for the functions listed below.
SAP
0, 1
2 to 32
33 to 54
55
56
57 to 60
61
62, 63
64 (default SAP)
* The following applies to PLC-to-PLC connections:
SAP 2 means a PLC-to-PLC connection to station 1
:
SAP 32 means a PLC-to-PLC connection to station 31
EWA 4NEB 812 6112-02
Function/Explanation
reserved
PLC to PLC connection via integrated standard function blocks
L2-SEND and L2-RECEIVE.
Layer 2 accesses
reserved
Standard connection
reserved
Cyclical I/O
reserved
Layer 2 accesses
SAP Numbers / Job Numbers
*
B-1