Power Fault at DO module

phang · Post by **phang** » 06 Mar 2018, 09:41

Hi,

I have a set of Revpi setup as following in the picture below,

: WhatsApp Image 2018-03-06 at 16.35.16.jpeg (209.29 KiB) Viewed 11173 times

All of them are connected to the single MDR-60-24, all gnd and wire are well connected, as the power are sometime experiencing inconsistent voltage (I have an UPS APC BACK-UPS 625 as the battery power for this system), the two DO are easily turned into Power Fault state and it won't recover until a power reset.

Are they supposed to be that sensitive? Or it is caused by other problem?
Is there any way to overcome this? Or configure the DO auto recover?

thanks!

Ingo · Post by **Ingo** » 06 Mar 2018, 13:14

Sorry, but the cable salad does not recognize whether everything is also connected below. Especially the protective conductor must be connected, which does not look like this with PI

: anschlussPI.jpg (115.66 KiB) Viewed 11163 times

should look like this from below

volker · Post by **volker** » 06 Mar 2018, 14:51

Ingo is absolutely right with his comment. You can't expect us to analyze your hookup with such a (sorry to say this) mess. The base of a reliant system is a reliant wiring.

A reset of the backplane bus as a reaction to a fault should never be automaticly done by the operating system (kernel driver) . The user's application needs to monitor the fault registers and should reset the piControl by ioctl if applicable or stop with any kind of alarm messaging (light indicator, SMS or whatever fits to the application).

phang · Post by **phang** » 07 Mar 2018, 05:25

thanks Ingo and Volker on the comment, will definitely do something with the cable.

The purpose of showing the picture is the RED LED indication on the DO module, sorry if that confuse you.
To explain the whole scenario, the system is running fine most of the time, except when there is power interruption (quick voltage drop) from incoming power source, however we have backup UPS that will quickly take place to supply constant power to the 24VDC and RevPi.
The reason that I raise the issue is that all the other module (Core, DIO and AIO) are running fine without giving fault except these 2 DO unit, so I am guessing if it is the sensitivity on the DO module or other reason

: 20180307_115751_HDR.jpg (172.51 KiB) Viewed 11104 times

volker · Post by **volker** » 07 Mar 2018, 05:48

Okay, I can see that there is most likely no EMC problem causing the trouble. switching from line to battery must be done in less than 1/2 sine of the mains according to EN61131-2 norm. That means the devices are built so that they can withstand a 20/2 ms power-drop without problems (RevPi Core can easily take up to 15-20 ms depending on the USB current drawn).
BUT!!! If you are using the same power for the outputs' current supply on your DO and the devices which are connected to the outputs are in on state during a power loss this could drastically reduce your gap time. Let's say you have connected a dozen relays, each drawing 100 mA @ 24 V, that would mean you are drawing 2,4 W x 12 = 26,8 W. As we have not built in any buffering for the output current supply the means the devices will go into a output power supply fault state.
There should be now way for the main supply of the module to deliver any backward current as there is a diode in front of the buffering C. And all the modules (Di, Do, DIO) are exactly the same (they are just parts placement variants). So I do not really understand why the main fault indicator is switching to red light. We will check this and try to simulate it in our lab in order to find out anything which might have been missed. In the meantime I would suggest that you ether build in a huge capacitor for the output supply or use a different power supply for the output currents (which is by the way a common practice).
Good luck!

phang · Post by **phang** » 07 Mar 2018, 06:29

ok, will add in a separated power supply for DO and a backup 24VDC battery to reduce the chances of fault.
thanks volker
cheers!

Ingo · Post by **Ingo** » 07 Mar 2018, 15:26

Hi,
it can have different clocks, try the problem once without DI and AIO module nachzustellen. Please run each DO separately on the Pi to test if this problem still occurs. if yes check if you have enough power and s.der 24V power supply and whether the PE with the 0 of the 24V are connected. If this is not a success you have to talk to Volker again.
Since I have no DO modules in use I can not say anything more. But most of the time it's up to the voltage supply.
to the emergency use also another power pack for testing to exclude errors in the present condition.

bye

Gregory · Post by **Gregory** » 03 Apr 2018, 06:05

Hello,

We wish to monitor the status (the power and out light) of our 2nd and 3rd DO modules. How do we do that? From the previous post:

The user's application needs to monitor the fault registers and should reset the piControl by ioctl if applicable

Where do I find these registers, or how do I find the value that turns the power to red light?

Thanks,

Gregory

volker · Post by **volker** » 03 Apr 2018, 16:45

please refer to this documentation:
https://revolution.kunbus.com/tutorials ... o-modules/
You will find a byte called "Status" which has bit coded flags. UV1/2 bits do correspond with input LED and bit 8-10 with output LED.

Power Fault at DO module

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