In a Profinet data exchange there is cyclecounter field. If you substract the previous cyclecounter from the current cyclecounter and you multiply it with 31.25 micro seconds you will get the cycletime of an IO-device. We have seen that there is a chance that the data exchange message are shown in wireshark in de wrong order. If you look at the cyclecounters of the Profinet data exchange messages it 100% sure that messages are shown in de wrong order. A profinet data exchange has a Vlan pdiority of 6. asked 23 Nov '15, 10:40  edwarddumay |
One Answer:
Shown in the wrong order or captured in the wrong order? Wireshark simply shows that frames as collected in the capture file. How this is done depends on how the capture files is created. answered 23 Nov '15, 11:23  Jaap ♦ |
The messages between the PLC and the switch are mirrored to the mirrorport of that switch. The IO-device is connected to another port of the switch. Wireshark captures the messages from the mirrorport of the switch
So, does the mirror port guarantee message order?
Thanks Jaap. Normaly the mirrorport keeps the messages in the right order. I have to ask the manufactuer of the switch if they can guarantee the message order on the mirrorport.