DLT's failing

In the space of 3 months I have had 4 DLT 5085DL fail. All have exhibited exactly the same problem. They simply stop sending commands onto the C-Bus. Looking at the application log or C-Bus diagnostics no instructions are sent for the units. All units display the LCD fine and LED's turn on and of on button presses. I can see them on the network they scan fine.

I have reset them and reprogrammed them and are still the same.

I have a total of 21 units and have been in service 2 years and 7 months. The first two died about 2 months have since been returned for repair to Clipsal. I purchased a couple of units as spares as replacements to fill the holes. To date the repairs have not come back so I don't know the verdict on those but suspect the last two will have the same fault.

I am concerned that more units will fall of the perch based on what is happening here. 4 having the same problem in the a short period of time with a little more than 2 years use is also of concern. Not to mention expensive.

Anyone else having this issue??

Regards,

Fleetz

 

you say you have "reset them and reprogrammed them and are still the same".

Does this mean that you could still inspect and edit the parameters with Toolkit?

If Toolkit could not talk to them, then I would say that there is a problem in the C-Bus processor (this product has two processors - one for C-Bus communication, and a second for the graphics)

If Toolkit could communicate with them, then the C-Bus processor must be working, and this then becomes a bit of a mystery.

One parameter which is critical for communication of lighting commands is the application address. Any chance that that had changed? If it changes to $FF (unused), the unit would display the symptoms you describe.

If you can program them with Toolkit, then download the 'live' parameters from the unit afterwards and find that the application address has changed (again), please let us know. This type of failure should be picked up by the repair staff at Clipsal, but they don't always let us know the details quickly to help track down a system issue. If this is the problem, no, it's not a bug, but it is a symptom of a possible system problem. If this is the problem, new units should solve the problem, but there is a chance, depending on the replacement units, that it may keep happening to you. Were the 'spare' units from the same batch?

Oh, and do you know the fw version / serial numbers of the units? Were they all the same version? this all helps track down the cause of the problem.

 

Hi Don,

Thanks for the prompt reply. Answered your questions in blue.

Regards,

Fleetz

One other interesting sympton is you can get the units to work if you reprogram them but will typically fail within an hour or so

 

hmm,

not what I thought it might be if the application address remains unchanged.

The only other thing I can think of is the EEPROM life limitation in the C-Bus unit. If the unit is configured to recover levels after a power interruption (this is generally not essential in a key unit, as the output units can also recover levels and override input recovery states after the network runs for a while), and there is one or more groups in the unit whose level changes frequently, then after several years of operation, it is possible that the EEPROM could begin to "wear out". Could this be the case?

If it is, you could prevent the problem from occurring by setting "restore to preset values" in the power fail tab, rather than "restore to previous".

Two years ago, DLT units were built with a microcontroller which incorporated EEPROM, and had a maximum guaranteed erase-write cycle count of 10,000 (at maximum operating temperature). The firmware was designed to allow individual bytes to fail, and had a mechanism to extend the life significantly, but there are limitations. 10,000 cycles is enough for two on / off state changes every day for over 20 years (only one state change requires erase), and we ran many tests in development which established that typically the EEPROM is up to well over 100,000 cycles before it fails (at typical operating temperature).

The most recent DLT production uses a different EEPROM chip which is guaranteed over 100,000 cycles(at maximum operating temperature), so EEPROM failure should never be an issue with new units. The EEPROM was changed not because of the life issue, but because of a change in C-Bus microcontroller.

 

Hi Don,

I understand EEPROM's, in another life I was the CTO of my company which designed, developed and manufactured TV Broadcast equipment. We used flash EEPROM a lot both standalone and embedded in CPU's. So I understand write cycles.

I have done a worse case calculation on the two initial units that failed and I have be hard in the calculation.....worse case 4000 on/off probably more like 2,500 but for the exercise let's use.

All of the DLT's are set to "Restore to Preset Levels" so I can set these to the ""Restore to Previous Levels". Can you tell me how that will effect the number of write cycles?

Interesting spec you quote in the last reply relation to the write cycle of EEPROM " had a maximum guaranteed erase-write cycle count of 10,000 (at maximum operating temperature)." What was the minimum or typical quoted???

Regards,

Fleetz

 

10,000 is the minimum number of guaranteed erase-write cycles, not the maximum. As Don says, actual values derived through testing were much higher.

 

I have 40 or 50 NEO switches in my home and had half a dozen switches that failed "semi-regularly" - they'd last about 8 months, then I'd have a spate of failures.

I have a few groups addresses that are "fake" - ie, there are not output units to remember the settings - and I'd been using the "restore to preset levels" for that reason. The final cause, once found, of my failures was that when the generator was runing, I was making the LEDs flash (dim/medium at night, and medium/bright during daylight hrs). This happened every 10 seconds (5 on/5 off) - the devices that failed were the ones that (a) flashed and (b) had restore previous state enabled.

After disabling the "restore previous state" I've had no further failures, thankfully.

 

That's interesting, RossW!

I welcome any feedback like this - I'm always concerned that though we designed C-Bus units for a 20 year lifespan, that we might have missed the mark a little. I think overall we did pretty well, as there are millions of units out there and the return rate is very low, with many early installations giving few problems. Personally, I'm very disappointed in a lifespan of only 8 months, and glad you got to the bottom of it. Hopefully the more recent production units will be free of this issue.



Fleetz, The manufacturer refused to provide either typical or maximum cycle counts at any temperature

 

Hi Don,

Understand wasn't looking for any garantee more an indication. I have no issue with the situation as I understand that products evolve and unless you build one you will never know how you can improve it.

This is about understanding the what we have and how we can extend their life. I can remember the number of times we developed products and just as the ink was drying on the service manual a better solution was available for the design......that's technology. After 40 years in it I have got that.

What I do appreciate is the open and honest manner you folks at Clipsal provide.

I will let you know what the reported problem is with the two units when they arrive back.

Regards,

Fleetz

 

Hi Don,

Just re-read your post and all DLT's are set to "Restore to Preset Levels" and have been from the get go. I assume this is the factory default setting as I never changed them.

I was about to change all 21 DLT but before doing it I went to your post to double check the suggested setting only to find they already are set to it. So they have been set to the most efficient EEPROM write mode.

I contacted the Clipsal guys here yesterday and the person who arrange for the 2 repairs isn't back until Monday so I will get the serial numbers and any report on what the corrective action is to you then.

Regards,

Fleetz

 

Another one just fell of it's perch!

This one is interesting in that it is located on our bedroom wall where there is a slider door. There is another DLT within a metre or so inside the entrance to the bedroom and get used a lot and is fine. The one on the slider is not used very often.

I would estimate that the one that has just died may have a 1000 keys at very worse probable closer to the 600 mark. Wife and I sat down and compared notes and we reckon within the range of 600 -1000 is real.

Given that this as all other unit were set to "Restore to Preset Levels" from the get go which if the EEPROM is the issue here as we suspect then I am now alarmed at the failure rate in 2 years and 7 months in operation. Especially seeing I have 21 on the bus.

Hopefully when Luke returns on Monday I will have news on the first two failed DLT's and see if our suspicions on the EEPROM are confirmed.

Regards,

Fleetz

 

Interesting numbers. Based on $300 purchase price.

If it is 600 cycles that is 50 cents an on or off
If it is 1000 cycles that is 30 cents an on or off



Fleetz

 

I seriously doubt that what you're experiencing is EEPROM wear-out. Best to wait for the analysis to be done before leaping to conclusions.

 

Hi Newman,

I agree with you.

The variation in range of estimated usages isn't making sense, I would expect that if it is an EEPROM that some more consistency would be more likely.

Interesting I reprogrammed the two here that have failed both have sprung back into life as did the the two that are in for repair now, anyway one of them has held up 4 days the other probably an hour or so . The two that are back there for repair now would work again for an hour to a few hours before letting go again.

I am thinking it might be more a electrolytic cap/s drying out....yes let's wait to confirm what it is but I agree the EEPROM is looking less as the suspect. Let's see.

I heard back from Brendan and Luke the Clipsal guys up here yesterday and was informed that the two units that are in for repair down there are still two weeks away from being ready. Will feedback when I have heard.

Regards,

Fleetz

 

Hi Ashleigh,

Nice to hear from you....hope you are well.

Agree with your comments on electros unfortunately in most electronic designs are a necessary evil. Interesting that the DLT appear not have any....scrub that theory!

I await with interest Clipsal's the findings on the two units there.

Regards,

Fleetz

 

Out of curiosity, what component is on a switch that will fail due to excessive heat? I have had two switches fail in a pump shed and I can only assume it was heat. It would be nice if I could replace a component to get them working again.

Mick

 

Hi Mick,

How goes it?

I will post here what they find. I suspect something to do with heat too but let's see.

Did yours still have an active LCD display, the buttons/LED's work ok but no commands get sent via C-Bus?

Regards,

Fleetz

 

It goes well, wet, but not as we as SE QLD at the moment.

Mine were not DTL's, just standard switches, but since the conversation was around failures and the electronics I thought I would ask. I would assume though that there are many components that are similar in the whole range.

I hope you have not received a bad batch as that will be pretty damn annoying if you have to swap them out. Its bad enough that you have lost four already - is this when the handbrake steps in and asks "would this have happened if we had put normal switches in at 10 bucks each"

Mick

 

Hi Mike,

Yes a few handbrakes that don't get the benefits of C-Bus up here...BUT....I have converted some over to the dark side too, that put a stop to those handbrakes!

Fleetz