Siemens SIMATIC S5 CP 523 Manual page 167

Communications Mode
CPU user program
CPU issues the "Send message frame" request
Word 0 Word 2
job No. Send length
A001 in bytes
H
CPU reads Coordination information
Word 0 Word 2
Coordina-
Byte 2: CBS
tion
(coordina-
informa-
tion byte
tion
for 'Send')
End here if CP has not
accepted the Send request!
CPU transfers 1st message block (8 bytes)
Word 0 Word 2
Data Data
CPU transfers further message block (8 bytes each)
Word 0 Word 2
Data Data
CPU transfers last message block ( 8 bytes)
Word 0 Word 2
Data Data
* only if Send length = 0 bytes
** relevant only in 3964(R) mode
Figure 7-9. Contents of the Transfer Memory for "Send Message Frame"
7-62
Word 4 Word 6
End-of-text
character significant
*
Word 6
Word 4
Byte 6/byte
Not
7: No. of
significant
subframes/
number of
message
**
frames
Word 4 Word 6
Data
Word 4 Word 6
Data
Word 4 Word 6
Data
CP
Not
- reads job number from
- writes coordination
8-byte
trans-
fer
memo-
ry in
the
CP 523
CP reads data from the
Data
transfer memory and stores
it in the Send mailbox
CP reads data from the
Data
transfer memory and stores
it in the Send mailbox
CP
Data
- CP reads data from the
- transfers message frames
- accepts no Send requests
CP functions
transfer memory
information into the
transfer memory
transfer memory and
stores it in the Send maibox
autonomously from the
Send mailbox to the peri-
pheral device
during this time!
EWA 4NEB 811 6044-02a
CP 523