Siemens SIMATIC S5 CP 523 Manual page 243

Summary
Table A-18. Return Info and Error Flags in the Coordination Byte 'Send' (CBS) in 3964(R) Mode
Bit
7 6 5 4 3 2 1 0
0 XX
H *
1
0 XX
H *
1 XX
H *
09
H
0B
H
0D
H
0F
H
15
H
17
H
19
H
1B
H
1D
H
00
H
* see error message
A-14
Description
Return info for job request A000
Send buffer free
Send buffer not free
Return info for job request A001
The info returned in the CBS following issue of Send
request A000 depends on the value in byte 1. If byte
H
1 is 00 , 0 in bit 7 of the CBS means that either a
H
parameter error was detected or that the Send
buffer is free but the current Send request cannot be
serviced because a Send request was issued following
transfer of a message frame which was not preceded
by a 'Check module status' request.
If bit 7 in the CBS is "1", the Send buffer is reserved
because the preceding Send request is still being
serviced.
If byte 1 is 01 , bit 7 = 1 means that the request was
H
accepted; the Send buffer is now reserved.
Errors flagged for A000
The receiver acknowledged with NAK during
connection cleardown
the receiver acknowledged with NAK during
connection buildup
Parameter error
Transmission aborted by receiver
QVZ (time-out) during connection buildup
QVZ (time-out) during connection cleardown
Initiation conflict, both link partners have high
priority
Break
Initiation conflict, both link partners have low
priority
No errors
H
H
and A001
H H
Receive data invalid
Receive data invalid
No data is transmitted
Receive data invalid
No data is transmitted
Receive data invalid
No data is transmitted
Transmission is aborted
No data is transmitted
CP 523
Response
EWA 4NEB 811 6044-02a