Fig. 52 Task Time Longer Than Ethernet Propagation Delay; Fig. 53 Task Time Shorter Than Ethernet Propagation Delay - Beckhoff BC9000 Documentation

Error handling and diagnosis
MissedCnt
Ideal configuration:
The task time is always longer than the Ethernet transmission time. An Ethernet telegram is transmitted at
the beginning of the task, and it returns it to the PC again after a period of time, t
smaller than the task time that has been set, the value in the MissedCnt counter remains constant.
Fig. 52: Task time longer than Ethernet propagation delay
If, after the task time has elapsed, an Ethernet telegram has still not arrived at the PC, only reaching it after
the next task has started, then TwinCAT will continue to work with the old input data. In addition, the
MissedCnt counter is incremented.
Fig. 53: Task time shorter than Ethernet propagation delay
This can have the following causes:
• The chosen task time is too short. Set
◦ 100 ms or more for TCP.
◦ 20 ms or more for UDP.
• Too many collisions in the network: use switches instead of hubs!
• The bus loading is too high: change to 100 MBaud!
• You are logged in to the BC9000, C900: this consumes additional processing capacity in the
Controller, which lengthens the response time.
The two following diagnostic inputs have different meanings, depending on the transmission type.
TCP/IP diagnosis
BoxState
Value Meaning
0x0000 No error
0x0001 No current inputs
82 Version: 4.0.0
. If the time t is always
Eth Eth
BC9000 and BC9100