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Communications Capabilities
12.3.2 Setting Parameters and Operation
Use the SINEC L1 parameter block to initialize the interface on the CPU (see Subsection 12.2.3).
For a point-to-point connection, assign "0" as the slave number for the CPU 943/CPU 944 (master
function only possible at 512). The partner in the link is always addressed as slave 1.
As long as interface SI 2 has been initialized for point-to-point connection, no programmer or OP
can be operated over this connector.
Note
Neither broadcasting nor interrupt traffic is possible over point-to-point connections.
As with the SINEC L1 local area network, data is exchanged via Send and Receive mailboxes that
the control program accesses with load and transfer operations.
The CPU operating system controls data transfer and stores the information in two coordination
bytes. The control program can read and evaluate both bytes. Figures 12-7 and 12-8 explain the
bits in the coordination bytes.
Receive Coordination Byte (CBR) (flag byte or high-order byte in a data word)
7
2
REC-PERM
0: The program can fetch data from the Receive mailbox. The operating system has
no access.
1: The operating system can fetch data from the local area network via the Receive
mailbox. The program has no access.
indicates irrelevant bits
Figure 12-7. Structure of the "Receive" Coordination Byte
12-18
0
2
Error
0: no error
1: receive error during last data transfer
Slave OFF
0: normal operation
1: node failure
LAN RUN
0: SINEC L1 local area network is in the "STOP" mode.
1: SINEC L1 local area network is in the "RUN" mode.
S5-115U Manual
EWA 4NEB 811 6130-02b
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