Recently, PROCENTEC released an aggregated TAP (Test Access Point) called EtherTAP for use with either Wireshark or Osiris running on Atlas or Mercury. I loved the device! It gave me the sense that I could finally see what was going on. Why did I feel this way?

Before we begin with the reasons why I wanted the TAP, let’s review what Osiris software running on either Atlas or Mercury can do. Osiris for PROFINET:

  • Uses Simple Network Management Protocol (SNMP) to monitor the network
  • Uses Internet Control Message Protocol (ICMP) to test the different segments
  • Uses various PROFINET commands to collect information on the network

With Osiris plugged into a regular port of any switch on the network, it would go about doing its job collecting information and letting you know who was on your network and how healthy your network was. It will report:

  • Who is on your network (showing both IP and MAC addresses)
  • What versions they are
  • Lost packets (either through SNMP or ICMP)
  • Network Loads
  • Overall health indicator/traffic light

This was good – very good. I particularly liked how Osiris would find cable issues which were virtually impossible to find any other way. When you saw that there were lost packets on a device, the first thing to check is the cable. The IO-Controller does not have a good way of seeing this while Osiris does.

Then PROCENTEC added the PROFINET commissioning wizard. This wizard took you through all the steps for the acceptance test outlined in the PI commissioning guideline (Order No. 8.082). This was simply brilliant because the steps outlined in that PI document were necessary but not easy to do. The wizard made it easy.

All and all, at this point, PROCENTEC had a great product, but I still missed something, and I did not know what until they gave me the TAP. I have been troubleshooting networks for over 30 years, and I always looked at the network from the PLC point of view. In traditional Serial protocols, it made a lot of sense. After all, if the PLC did not see things right, then you knew you were in trouble. Osiris was giving me everything I needed except for the view from the command chair – the PLC.

Adding the EtherTAP to Osiris was the icing on the cake for me. Now, I could see cycle times and jitter as viewed from the PLC point of view which is important, and I no longer had to trust that the switch was calculating it correctly. I had one spot for Alarms, and it could record Wireshark traces for the hard issues.

Speaking of which, for a small percentage of problems, having Wireshark as a backup is very useful. The EtherTAP gives you a permanent access point that is not depended on port mirroring. I always had like port mirroring in the past. However, as I have been learning more about switches and working more with them, I have realized a sad truth – Just when you need port mirroring the most is also the point that it is most likely to let you down. As network load goes up, the resources of the switches get stretched and the switch will begin to drop packets and port mirroring brakes down. This is also the point where you need port mirroring to work. Therefore, having the EtherTAP between your PLC and the switch is the best practice. Add in the permanent monitor of Osiris running on Atlas and your troubleshooting toolkit is complete.