Dinamousers | TM44 OCD (Over Current Detection)

TM44 OCD (Over Current Detection)

Posted by Snoopy33 on 2026-02-26 17:10

Hi Leon,

We have fully equipped our system with TM44 and OC32, is operated by iTrain and is running quite fine.
We are having issues with a very long train consisting of 1 locomotive, 13 carriages and 1 cab trailer. Everything with digital decoders and carriages with indoor lights. This train normally runs smoothly, once the super caps of the carriage illumination are charged. Sometimes, iTrain shows a red blinking frame on the block symbol, that indicates Over Current Detection (OCD). Once the caps are charged, the train runs smoothly on all blocks but only if it is alone. As soon as there are other trains running on blocks connected to the same TM44 we constantly see the OCD errors.

We've measured the total current of this specific train using a digital Multimeter. We see a total current of 600mA.

I might remember to have set the OCD reaction time to "slow" on all TM44. In my opinion, a single block should be able to provide 2A without problems.

So my questions are:

- Could it be possible, that the 2A is reduced to a lower value when there are trains on different blocks on the same TM44?
- What can we do to overcome this issue?

Thank you very much in advance for your appreciated answer

Michael Schaefer
REAK
Rheintalischer Eisenbahn Amateur Klub
www.reak.ch

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Posted by Leon van Perlo on 2026-02-27 00:14 Netherlands

Hi Michael,

We have fully equipped our system with TM44 and OC32, is operated by iTrain and is running quite fine.
Well, that's good to read.

.....
- Could it be possible, that the 2A is reduced to a lower value when there are trains on different blocks on the same TM44?

No. At least it is definitely not programmed that way, so if there is any such effect it is unintentional.
This particular behaviour has never been reported before and it would require additional testing to verify. However, the whole OCD thing needs revision anyway to support those "supercaps" better. If it is just inconvenience and does not impose a real problem for you now I'd suggest you wait for that.

Kind regards, Leon

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Posted by Snoopy33 on 2026-02-27 01:23

Hi Leon,

Thank you for your answer.

Hmm, it's just a pity that we can't use this pretty a also expensive train. Probabply there are other with similar problems.

Have you got any idea what we can do or how we can give you more information, so you are able to trach it down?

Best regards, Michael

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