Mesa 5i25 + 7i77 Communication Error

Hello,

we have a milling machine that runs Linuxcnc over 7 years, with Mesa 5i25 + 7i77 cards.
A few days ago machine starts to give these error messages, for every 10-20 minutes:


After error i restart Linuxcnc and it works more 10-20 minutes.
The messages seems to inform some power supply failure but when i pull out 5VDC connector from MESA 7i77 then i get this messages (that not same from the first photo. Here is a plus Extra Character message).



If i pull out the Field Voltage 24VDC connector from Mesa 7i77 i get these messages (that not the same from the first photo too, here is a Undervoltage extra message).



What you think what this messages from first photo exactly means? And why i get it?
Maybe problem with mesa cards? Unfortunately i dont have other Mesa card to swap it with old, but if someone 100% sure that problem is with cards, i would buy new.

Every power supply is ok, i measure 5,0VDC, and 25,0VDC.

Attila.

It does look like 5V power issue (since you lose both serial interfaces at once)
Can you monitor the 5V power at the 7I77 (say at an encoder connector) when this happens?

Hm, i suspected that problem is from PSU, therefore i install new (MeanWell 5VDC / 2A) PSU, and change the capacitor and rectifier for 24VDC.
But problem still exist.
Between 5i25 and 7i77 is an ISOL card. Maybe problem is with 5V of PC PSU? But PC and OS works ok.

I will check 5VDC with oscilloscope.

Maybe in encoder cable has a short circuit between 5V and GND... ?

Yes, 5V loss on the PC side of the isolator would also cause the same symptoms
so I would check both 5V supplies when you see the issue.

7i77-undervoltage fault means that +5v supply voltage level too low on the 7i77 itself.
Assuming that the encoders are fed from the same +5v line-It should be encoder or its damaged wiring fault.

Hello,

I have similar errors. Did you find any solutions for your problem: Maybe it could help me too...

If you get all those errors, its most likely the there is an issue with the 5I25 card access from the PC.

Either the 3.3V PC motherboard rail is so low that the card has been reset or
there is a contact issue (try removing the 5I25 card, cleaning the PCI contacts and re-installing)