Siemens SIMATIC ET 200SP Manual page 101

Status nibble (byte 1 of the digital input data)
Bit 7 Bit 6
1 1
1 1
0 1
Example
The table below indicates the behavior of the status nibble display as a result of the device
status and the command processing in the user program:
1. Switching on the AS-i voltage of the CM AS-i Master ST.
2. The user program transfers a command (e.g., Write_parameter) to the
CM AS-i Master ST with an asynchronous write access.
3. The AS-i master ends the command. The user program can read the
return value
4. The user program reads the 2 byte return value with an asynchronous
read access.
5. ... Further program processing ...
6. The user program transfers a command (e.g.,
Read_expanded_lists_and_flags) to the CM AS-i Master ST with an
asynchronous write access.
7. The AS-i master ends the command without errors. The user program
can read the response data.
8. The user program reads 32 bytes of response data with an
asynchronous read access.
AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004
Bit 5 Bit 4
0 1
1 1
0 0
Action
9.3 Command interface with controllers of other manufacturers
Command processing has been ended without errors. An
asynchronous read access can be used to retrieve 56 bytes of
response data from the AS-i master.
Initiation of a new command by the user program is possible.
Command processing has been ended without errors. An
asynchronous read access can be used to retrieve 221 bytes of
response data from the AS-i master.
Initiation of a new command by the user program is possible.
Job processing is complete. The response data or return value of the
previous job has already been read by the user.
Initiation of a new command by the user program is possible.
Using the command interface
Meaning
Response in the status nibble
1110 ... 1000 ... 1110
B B B
0010 (briefly, dependent on command)
B
0001
B
0100
B
...
0010 (briefly, dependent on command)
B
1011
B
1011
B
...
101