Created Date: October 13,2017

Created by: Michal

Dear Users

I was ask to support one machine. The Koyo PLC is a new type of PLC for me, so I woulike to ask you for support. I have connected to the PLC. I have checked the alarm list. I have attached all screens and one of them present error number E250 I/O bus failure.Can you help me and find a solution for it? Of course if the failure occurs then everything is shut down ...The PLC system is quite big, it has a lot of modules. The PLC is composed of 3 racks. The detailed information are presented at the pictures. The data at the picture with failure is probably wrong, I will correct it.

I appreciate your help and support.

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Created Date: October 19,2017

Created by: Michal

Dear Do-more PE thank you very much for your answer. According to your advice I have changed the position of the switch (the last one on the right side). Nothing has changed, still I receive the same alarm message.

This is only a digression. Current situation

rack number 1: switch position is "ON "

rack number 3: switch position is "ON "

rack number 2: switch position is "OFF "

Please note that connection order is following: rack 1 -> rack 2 -> rack 3, but the rack in the middle is the third one (D2-06B-1).

I have ordered a new CPU. I'm waiting for the pack, it should arrive at the beginning of the next week. All base units have been replaced.I have also installed one new D2-CM module (rack number 2).

Do you have any other suggestions? Thank you in advance.

Created Date: October 20,2017

Created by: Michal

@ Do-more PE

I sent an email do technical support. A ticket was created: 01413310. I got an answer from technical support:

"Hello Michal,

The problem may be a bad PLC or base.

Try removing all cards from the rack except the PLC. Program the PLC with a single end statement to see if you get the same error.

Best regards, "

So I am performing steps according to support departem advice. The point is that this error occurs once per each second (maybe third) day. The PLC does not stop every day.

I live in another timezone (+6h), but maybe I should try to phone the support guys.

Created Date: October 20,2017

Created by: Do-more PE

That is a very important piece of information. You should make sure that the EM modules on the end of each base are tight. Also, you should try changing the cables for the EM connections.

One other thing I noticed is that there are multiple connections to the ground terminals on the PLC. If the Grounds are daisy chained, this can introduce noise into the PLC system. Make sure all grounds go to a single ground point in the system.

Created Date: October 21,2017

Created by: Michal

Thank you for information, I really appreciate it :).

The text below concern EMC disturbances

This machine is composed of many parts: it has huge motors, small pumps and so on. The operators told me that PLC stops everything even if small pumps are working. This is reason why I thought that EMC disturbances can not be the source of my problem. Two weeks ago machine (production line) was turned off. The technological breakdown lasted more than week. During this one week the PLC did not stop even once.

Operation plan:

1. EMC filter

I'm going to instal an EMC filter. I will instal one EMC filter for all bases (2x D2-09B-1 and 1x D2-06B-1), is it correct?

2. UPS (Uninterruptible Power Suppl)

I'm also taking into consideration and UPS (Uninterruptible Power Suppl) power source. Can I power all bases from an UPS power source?

3. Ground cables

I will conect all grounds signals to one point (the main connection point of the machine). This machine has common PE and N line at main power connection point. The PEN (PE +N) is divided into two separate cables at main terminals block of the machine.

4. D2-EM connection

I will check the connection between module D2-EM and base unit. I will clean all pins (connection points)

The machine is composed of three identical sets. Unfortunately one set of the machine is damaged. Yesterday the operators destroyed huge shaft. The problems with the PLC caused damaging the machine.

I will inform you about the results of all tests.