Siemens SIMATIC S5 CP 521 Manual page 147

ASCII Mode
CPU job request: Coordinate data transfer
To coordinate data transfer, job A0
the meaning of bytes 1 to 7.
Byte Value
0 A0
H
1 01
H
2 01
H
3 00
H
4 00
H
5 00
H
6 Irrelevant
7 Irrelevant
Byte 1: You allocate send permission for a message by setting bit 0 = 1.
This initiates data transfer. The CP 521 resets this bit after passing
the message on to the peripheral device.
Bytes 2 u. 3: Bytes 2 and 3 indicate the message length. The length can lie
within the range 0001
the receive device because the send length is not transferred, in
contrast to the end-of-text character.
In the case of a message length of 0, the CP evaluates the end-of-text character. If
both send length and end-of-text character are 0, there is a job error.
7-24
is written into byte 0 of the PIQ. This defines
H
Table 7-14 Coordination Job
Meaning
Job: Coordinate data transfer
Send message (send bit)
Send length (here: 256 bytes)
Send length (here: 256 bytes)
Not significant
Not significant
to 0100 . You must have set this length on
H H
CP 521
GWA 4NEB 812 6030-02b