Siemens MOBY FC 56 Technical Description page 126

Programming MOBY-ASM on PROFIBUS-DP-V1
Two states must be coded.
1. Command state (command counter) to tell the user whether a new/next
command may be transferred to the MOBY-ASM
2. Acknowledgment state (acknowledgment counter) to tell the user whether a
new acknowledgment from the MOBY-ASM is waiting
User evaluation of the acknowledgment state must always be given highest
priority (i.e., when the user wants to send a telegram to the ASM but a
telegram from the ASM is waiting to be fetched at the same time, the
telegram from the ASM must be fetched first).
Both the command and the acknowledgment state are coded in 2 bits each. Both
states are stored in a byte (see appendix B.1).
B-4
FC 56
J31069-D0155-U001-A0-7618