Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
Explanations regarding Fig.10-2:
Computational time required by the position controller
DP cycle time: DP cycle time
Data exchange time: Total of transfer times of all
Master time: Shift of starting time of the NC
Global Control: Broadcast message frame for cyclic
synchronization of the isosynchronism between DP master
and DP slaves
User data exchange between DP master and DP slaves
Acyclic services (e.g. DP/V1, token transfer)
Reserve: "active break" until the equidistant cycle has elapsed
MD10062 POSCTRL_CYCLE_DELAY (position control cycle offset)
The following setting is recommended as the orientation value for the position
control cycle offset:
The DP cycle time is equivalent to position controller cycle of the SINUMERIK
Display using HMI Advanced (Option):
Operating area switchover > Diagnosis > Service displays >
Alarm: "380005 PROFIBUS DP: Bus access conflict, type t, counter z"
t = 1
The position controller cycle offset has been chosen too small. The cyclic
PROFIBUS DP communication with the drives was not yet completed with
the start of the position controller.
Remedy: Increasing the position controller cycle offset.
t = 2
The position controller cycle offset has been chosen too large. The cyclic
PROFIBUS DP communication with the drives started before the position
controller was completed. The position controller requires more
computational time than available within the DP cycle.
– Remedy: Reducing the position controller cycle offset
– Remedy: increasing the DP cycle time.
The DP cycle time is set using STEP7 "HW Config". See Section 7.3,
10 NC Start-Up with HMI Advanced
10.3 System data