KROHNE ALTOSONIC V Modbus EN - Manual (Page 26)

ALTOSONIC V
ModBus Manual 0300 rev07 E 7.30855.35.00 Page 26 of 64
Example of reading a status flag from an UFP-V in slave mode
The status flag is read by the master.
1. If the status flag is active,
the master uses this state to perform its actions and sends an acknowledgement to the UFP-V by
setting the accompanying ACK_flag to 1.
Now the UFP-V updates the status flag with the actual status.
Note that in this mode the status flag remains active until the acknowledge is given.
2. If the status flag is not active,
the master removes the acknowledge by resetting the ACK_flag.
Example of reading status flag 0 from an UFP-V in master mode
1. The first poll block sends the status flag to the master
2. If the status flag is active, the master uses this status to perform his actions and sends an
acknowledgement to UFP-V by means of setting the accompanying ACK_flag to 1.
3. The next poll block reads this ACK_FLAG and updates it in the UFP-V,
now the UFP-V updates the status flag with the actual status.
3. If the flag is not active, the master removes the acknowledgement by resetting the ACK_flag.
As long as the ACK_flag is active the status flag is updated every 35 milliseconds.
If the communication speed is known, choose the 5.4 FLAG_HOLD_TIME large enough to give the
host the possibility to detect the state of the flags.
To set-up a more secure system use the acknowledge method. A disadvantage is the increase in
communication time.
5.4 FLAG_HOLD_TIME is located in the coms0300.dat file.
See also chapter 9.4 Appendix D: Coms0300.dat file