Siemens SIMATIC S5 CP 523 Manual page 159

Communications Mode
All information presented in the next three tables (7-29, 7-30, 7-31) is relevant in 3964(R) mode
only.
Table 7-29. 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
* See Error Flags
7-54
Description
Return info for A000
H
Send buffer free
Send buffer not free
Return info for A001
H
The information returned in the CBS
following submission of a Send request
(A001 ) depends on the value in byte 1.
H
If byte 1 contains 00 , CBS bit 7=0 means
H
either that a parameter error was
detected or that the Send request could
not be serviced even though the Send
buffer was free, as it was not preceded by
a"check module status" request.
CBS bit 7= 1 means that the Send buffer is
not free because the previous Send
request is still being serviced.
If byte 1 is 01 , CBS bit 7=1 means that the
H
request was accepted; the Send buffer is
now reserved for this request.
CP 523
Response
EWA 4NEB 811 6044-02a