Siemens SIMATIC S5 CP 523 Manual page 88

CP 523
The following is a schematic of job request processing. Entry of the print request in the message
buffer is not shown in the figure. It is only important for the user to know if a job request has been
accepted by the CP 523 and will be serviced.
CPU transfers new data to the CP 523 in
words 2, 4 and 6, if required
CPU transfers the new job request to the
CP 523 in word 0*
CP checks: "Last job not
completely processed?" or
"Messsage buffer full?"
CP services CPU request
CP stores the following in transfer
memory
- Status of the CP 523 in byte 0
- Status of the printer and current
clock data in bytes 1 to 7
* 5.2
Figure 6-7. Schematic Representation of Job Request Processing
EWA 4NEB 811 6044-02a
NO
CPU reads byte 0 of the transfer
memory, evaluates the error flags and
reenters the request in word 0*.
CP flags the following error message in
byte 0 of the transfer memory
• "CP in restart routine"
YES
current data in bytes 1 to 7 is not
valid!
or
• "Job / message buffer full"
bytes 1 to 7 contain the current
clock data!
Print Mode
6-33