Command Processing: Command By Command - Siemens MOBY FC 56 Technical Description

B.2 Working with the ASM
Command processing is handled command by command.
This means that, after each command, the user must wait for the acknowledgment
(result) before the next command is sent to the ASM. This type of programming
involves the following characteristics.
S Simple programming of a function block
S No optimal-speed data transmission for several consecutive commands
The following diagram shows the procedure used for command and
acknowledgment communication between user (DP master) and MOBY-ASM.
Command
Ç Ç
DP master
Ç Ç Ç Ç Ç Ç
The command and acknowledgment telegram is a non-cyclic DP/V1 telegram with DP/V1 response.
Start is only permitted after a change in the command and/or acknowledgment counter.
Ç Ç
Change in the command counter. New state = old state + 1 (cyclic word)
Ç Ç É É
Change in the acknowledgment counter. New state = old state + 1 (cyclic word)
É É Ç Ç Ç Ç
No change in the cyclic data
Figure B-5

Command processing: command by command

Command chaining and command repetition
These features are currently not supported in filehandler mode.
FC 56
J31069-D0155-U001-A0-7618
Processing a MOBY command
Ç Ç Ç Ç Ç
Ç Ç Ç Ç Ç Ç Ç Ç Ç É É É É Ç Ç
Communication
Acknowledgment
with the MDS
Processing the
1st command
Programming MOBY-ASM on PROFIBUS-DP-V1
Command
É É Ç Ç Ç
É É Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç
Communication
with the MDS
Processing the
2nd command
Time axis
Ç
É É Ç MOBY-ASM
Acknowledgment
Direction of
communi
cation
B-7