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What are possible causes of a web page statistics Overrun fault on an ATV61/71 series drive with Ethernet IP communication card?

Issue:
What are possible causes of a web page statistics Overrun fault on an ATV61/71 series drive with Ethernet IP communication card?

Product Line:
Altivar 61 / Altivar 71 series drives.

Environment:
All models and serial numbers where Ethernet IP option card, part number VW3A3316, is installed.

Cause:
Information not available in current documentation.

Resolution:

The Overrun counter is a standard Ethernet Diagnostic. The value is provided directly by the Ethernet component used on this card.

The overrun shows the number of times that the receiver hardware was incapable of handing received data to a hardware buffer because the input rate exceeded the receiver's capability to handle the data.

This behavior can be observed when a peak of frames appears on the network.
The origin of the frame peak can be linked to the network load.
Burst of request could be generated on the network when some device restart or Power ON on the same Ethernet network (like for example PC with proxy server). This type of device initialization generates a lot of broadcast frame on the entire network. These frames will be seen by the drive.

A point to check will be to make a network analysis in order to have an idea of the network load.

Then if it appears on only one card:
Dedicated services are launch only on this card.
Even if the protocol selected is Ethernet/IP, the card embeds Modbus TCP server (on webserver for example). These Modbus TCP servers stays accessible. PLC or computer (webserver, specialized tool) could send Modbus TCP request to one card.
So you will have on the same card, CIP implicit exchange + Modbus TCP request. If the rate of those exchanges is really fast, you are in similar condition that burst of request describe before but here only located on one card.
Card could be defective
For this it’s needed to replace the card and send back the card for expertise.


Several verification could be check:
First check the network load
On device where you do not see Overrun fault and on device with Overrun counter increasing. This will give several indications
Compare the Frames load on several drive (one good and the bad one)
Have an overview of all frames send see by this drive with Overrun counter.

Swap 2 card
Take one card where there is no Overrun and swap it with “bad” card.
If issue follow the card, it will be mandatory to analyze this card. But before analyze, we need to have the result of network measurement, and know what are the service used on this card
implicit messaging (what is the speed RPI)
explicit messaging (what frequency)
Modbus TCP exchange used (if yes what is the frequency)
Webserver used or not
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