Transmitting Data - Siemens SIMATIC S5 Manual

S5-95U, SINEC L2
4.3

Transmitting Data

There are two prerequisites for transmitting data:
• The parameters for the locations of SF and CBS are set in data block DB1 (see section 4.2).
• The transmit data,
station address of the receiver) have been transferred to the send mailbox.
Figure 4-4 shows which information must be stored in which send mailbox location.
Example: Send mailbox in the flag area
(starting with flag byte 0)
FY 0 "Net data" length in bytes
(1 to 242)
*
FY 1 Receiver's address*
FY 2 1st data item
FY 243 242nd data item
* 1 to 31 = L2 station address (active stations)
255 = Broadcasting (to all active and passive stations, see section 4.6)
Figure 4-4. Structure of the Send Mailbox for a Standard Connection
EWA 4NEB 812 6112-02
additional information (length of the transmit data ("net data"), and the
Data Transmission Using a Standard Connection
Example: Send mailbox in the data block
(starting with data word DW0)
DL
DW 0 "Net data" length
in bytes (1 to 242)
DW 1 1st data item
DW 121 241st data item
--
DR
Receiver's
address*
2nd data item
242nd data item
4-5