The power company has been working on the electricity supply in my locality, and today whilst I was out at work, there was a power cut.
When I returned home I discovered that all four of my LW381 Basic On/Off Plug-in Sockets had switched on and therefore the lamps connected to them had been on for much of the day.
I thought the plug-in sockets were supposed to default to off once the power came back on after a power cut. Is there a setting change I can make so that they default to off?
This unfortunately is one of the endearing features of the basic plug in sockets and the flawed thinking of the Lightwaverf software development team.
Devices do in general default to off after a power off period as do the basic plug in sockets. However, devices can be made to default to power on by turning the link off, putting a device in pairing mode, and turning the link on.
At power up the link sends a special command and any device in pairing mode will hear this and remember this. Any subsequent power up cycle and those devices will respond and then turn on.
For most devices, this works OK as you have to explicitly put them into pairing mode with some button push. The basic plug-ins though don’t have a button and go into pairing mode when powered up for a few seconds.
So a power up of links and plug-ins together can cause them to be in pairing mode and learn the new power up behaviour. Subsequent power ups can then cause the plug-ins to turn on.
Once the plug-ins have learnt this, they will stay like this, so need to be cleared down completely and repaired normally.
This basic flaw was pointed out to Lightaverf a long time ago, and could have been avoided by a more sensible strategy on setting up power up behaviour like having a specific menu command on the link to set it up.
Thanks for your reply.
I’ve just tested a power off/on cycle on the plug-ins alone and they remained off when power was restored. So as you say, it’s probably the link and plugins powering on together that causes the issue, although I haven’t tested that yet.
I raised a ticket with LightwaveRF support yesterday asking for a workaround/fix but I don’t hold up much hope.
I have a concern about this behaviour as this just happened to me yesterday, and I found this post after googling the problem. I use the plugins for a few devices which should NOT come on by default following a power cut.
If I understand correctly – a first power cut will result in all of the plugin devices becoming paired with the links “power on” transmission when the power comes back on, but will remain off (i.e. no way of detecting this has happened as would go unnoticed). A second power cut (even to just the lightwave link itself and not to the plugins) would then result in the plugins reacting to the “power on” transmission and turning on.
Very dangerous if the plugin devices are used to control something like a hair straightener as could result in very serious consequences!
How did you raise the ticket with LightwaveRF support? I would like to raise a similar ticket or vote up yours if thats possible!
However, I would rate the chances of something being done for this as so close to zero as makes no difference.
The basic plug-ins LW381 were superceded by the more advanced plug-ins LW321 which have a separate pairing button and therefore do not suffer from this behaviour. The latter also allow mood control and up to 6 pairings (3 for the basic).
The basic plug-ins are still available and are attractive because of their significantly lower cost, but you then have to be aware of this behaviour.
If one has automation on top of normal link then it is possible to issue commands on power up to put all devices into a default state when power is restored.
Thanks for the reminder, I have just updated my ticket as I haven’t had a satisfactory response from them yet. They responded in December saying the plug-ins do default to off, so I replied explaining that it was the Lightwave Link that was turning them on.
As btidey says though, I very much doubt they’ll do anything about fixing the issue.
LW321′s were not an option when I bought the basic plug-ins because they’re not suitable for LED loads.
The 381 offers no extra suitability over the 321 for switching leds. Both should work fine with loads up to 3000w
Ah, OK. I was going by what it says in the LW321 Installation Guide “…The Plug-in is not compatible with LEDs or low energy CFLs and may not perform properly…” I’ve tried an LW301 plug-in dimmer and I know it left the LED glowing even when off, like the wall switches do with some LED lamps.
So LW321′s or inline relays would sort out the issue, but at the moment I’m not going through the extra expense of selling my LW381′s and replacing.
The LED comment is just a bit of cut and paste nonsense.
Both varieties of plug in sockets work by actuating a relay contact between the live input and the live output and can handle a 3kW load (resistive).
LEDs would not be a problem.
Where there might be an issue is with highly inductive loads such as heavy duty motors, particularly if they do not have any in built suppression. Arcing across the relay contacts can occur when these loads are switched off and these can cause the contacts to stick together and the switch then stays on even when turned off. Some people have reported this problem.
LightwaveRF are having a problem understanding the problem.
“Dear Lightwave Customer Support,
I have not heard anything more from you with regard to this problem.
Is it possible to fix with an update to the firmware of the Lightwave Link, so that it doesn’t send out an ‘on’ command to the LW381 devices when it powers up?
I look forward to hearing from you…”
Thanks for this query again. Unfortunately this is not an issue that could be fixed with a software update or as such. And something we have not heard from any other customers, so it difficult for us to troublshoot this, but how often do you get a power cut if I may ask as this is unusual !?
We are happy to test your units if they are sent to us however.
I raised this issue in the LightwaveRF community forums, and I can assure you that I’m not the only customer to experience the issue.
One forum member has explained his understanding of the problem as follows: “Devices do in general default to off after a power off period as do the basic plug in sockets. However, devices can be made to default to power on by turning the link off, putting a device in pairing mode, and turning the link on. At power up the link sends a special command and any device in pairing mode will hear this and remember this. Any subsequent power up cycle and those devices will respond and then turn on. For most devices, this works OK as you have to explicitly put them into pairing mode with some button push. The basic plug-ins though don’t have a button and go into pairing mode when powered up for a few seconds. So a power up of links and plug-ins together can cause them to be in pairing mode and learn the new power up behaviour. Subsequent power ups [of just the Link] can then cause the plug-ins to turn on…”
This seems like a plausible explanation. Is it correct? If so, then I don’t see why the software on the Link couldn’t be altered over the Internet so that it doesn’t send ‘a special command’ on powering up. However, I am happy for you to exchange my 5 x LW381 units for LW321’s instead.
It is easy for you to troubleshoot if you have any Generation 1 Lightwave Link and any LW381 in your workshops.
Regrettably, it is not unusual to get power cuts in rural locations of the U.K. Some may just be a few seconds long. Having plug-in’s switch themselves on when a property is unoccupied is an expensive waste of electricity and, even if it only happens once, could be a safety concern if something other than a lamp is attached…”
Thanks for your reply.
Firstly, The forum is not monitored or maintained by LightwaveRF staff. We can only comment on the tickets have been received by LightwaveRF directly and this is not a problem we have heard of from any other customers.
Although the forum has enthusiastic LightwaveRF customers, please note that the information on there is not verified by LightwaveRF at all and so it is not necessarily correct.
The user on the forum is correct saying that devices do default to OFF mode once you have a power cut, but you can change this if wanting them to go to an ON position after a power cut, so from my understanding you have never gone through this procedure to change this as you did never want to have the sockets to be ON after a power cut. So in order to change the status after a power cut, you disconnect the lightwave link from the mains, put your device into pairing mode, and now pur the power back to the unit, so by doing this all your devices will revert to ON position after a power cut. But clearly you have not carried these steps…”
OK, so you have agreed that “…in order to change the status after a power cut, you disconnect the lightwave link from the mains, put your device into pairing mode, and now pur the power back to the unit, so by doing this all your devices will revert to ON position after a power cut…”
Then you say “…But clearly you have not carried these steps…”, well I haven’t intentionally carried out those steps, but you must understand that the LW381’s automatically go into pairing mode with no user intervention after cycling the power off and back on.
Therefore, because of they way they have been designed, the LW381’s will always change back to reverting to ON after a power cut unless the Lightwave Link can be programmed not to change the status.
You say that it’s not a problem that you have heard of from any other customers. That may be true, but it doesn’t mean to say the problem doesn’t exist. I contacted you in December and it’s easy for you to replicate…”
I have submitted a separate support ticket on this issue, if they are that much in denial. I explained the exact steps and behaviour causing this.
Like many support desks, they seem to focus on one item in a report and do not bother to try to understand the actual problem even if it is spelled out in detail.
I remain pessimistic that anything will be done, but at least they now have at least 2 reports of this behaviour.
So I got my reply back from support:
I am happy to inform that we have replicated this scenario on site with various LW381 units and all units revert back to OFF state. after a power cut/ I am not sure how I could troubleshoot your issue any further I am afraid.
Perhaps they’ve gone faulty as a result of the power cut/surge, we are not sure ! You could always get the better plugin sockets LW321.
They probably didn’t turn on both link and plugins. I have given them even more detailed instructions, and told them the units are not damaged.
Bit more info on this.
Lightwaverf say they cannot reproduce despite multiple attempts powering up link / plugins together.
I did a bit more experimenting.
1) Plugins stay in pairing mode for about 8 seconds after power up.
2) By using a lightwave rf message sniffer and videoing the display on my link then I could see the power up message is sent immediately after the ‘Time Not Set’ message is displayed.
3) The Time Not Set message appears on the screen around 8 seconds after a link power up.
So it is touch and go whether the plugins are still in pairing mode when the message is sent.
It is also possible the link timings will be a little different depending on whether the link has a display.
I have let support know my findings. I believe one can reproduce it more reliably by powering up the plugins a few seconds after the link so they are more likely to be in pairing mode when the message is sent.
It would also mean that delaying or moving the power message in the link by a few seconds would significantly decrease the risk of this occurring.
Today I got exactly the same reply from them that you quote above.
Thanks for raising a ticket and for the experimenting and dialogue you have been having with them on this matter so far.
I have the Lightwave Link without a display.
I had exactly the same problem a short time back. I had a short sub station blowout which did the auto reset with the power, so it was not off for long.
Still I came back down stairs to find the television and satellite receiver along with the surround sound amp turned on. I have these defaulting to off normally at certain times, so imagine my surprise.
A few short tests.
With power off and back via by the mains trip, repeated the same problem, sockets defaulted to on, every time after power loss.
Next check, power down the link by removing power lead, wait a short while then power back up, had exactly the same effect.
Last check, remove socket from mains leaving link on, then plug back in. The plug socket flashes to get its link back(light steady) but stays off. This then works as normal. Until the next power outage, that is.
As far as the link being established at power up,being the problem, that should not be an issue if the device is off. I tried setting a socket up, by having a load plugged in and setting up the socket, the load was a TV which remained off through the setup process, so the socket is clearly off at setup time. So shouldn’t the default be off, one would think so, unless it is something else at fault.
Oops it is the lightwaveRF link box that is causing the problem, along with the way it is re-establishing communication, as already mentioned.
Forgive me for saying so, but this can be fixed in firmware/software. I have no idea which MCU these link devices use, but I have programmed critical system responses into many devices, which default all operations to known states, even putting delays in so certain operations are scheduled correctly. Pity they didn’t read the MISRA standards before programming
I can possibly do a work around, now I know the facts, but that would need some work to do something that should be done by default.
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