Siemens SIMATIC S5 CP 523 Manual page 157

Communications Mode
Special features of "3964(R) mode"
In "3964 R" mode, you receive different return info after submitting a "Coordinate data transfer"
request than you receive in Transparent or Interpretive mode. The return info for "3964(R) mode"
is presented separately in the following.
In "3964R" mode, there are three job requests which provide different return info:
1. Job request A000
H
2. Job number A001
3. Job number A080
Job number A000 , which checks the status of the CP 523, should be submitted prior to every
H
Send and Receive request.
The following tables list the status information returned by the CP 523 in all three cases.
Byte
0 Status byte
1 Permission to send and receive
2 Coordination byte 'send' (CBS)
3 - 7 Not significant
7-52
interrogates the status of the CP 523
is a Send request
H
is a Receive request
H
Table 7-26. CP 523 Status Information for "A000
Description
CPU can neither send nor receive
CPU can send
CPU can receive
CPU can send and receive
CP 523
"
H
Possible Values
50
H
00
H
01
H
80
H
81
H
Table 7-30
EWA 4NEB 811 6044-02a