DMX safety for non-lights usage
- Thread starterSanTai
- Start date
I guess you don't do any big Rock shows then...
All companies I have worked with or seen on a stage use it when the systems becomes more complex.
Sigma Services, for example, which I believe are big on flames in the US use it in their products.
For a system with TÜV-sticker look at LunatX.
Can you tell me why?
Or is it just a general it might be dmx black magic voodoo thing?
DuckJordan
Touring IATSE Member
I don't trust it and neither does our fire marshal. And I wouldnt call Disturbed and rob zombie small.. Please as a student try not to put your foot in your mouth.
I am sorry, I do not see how the fact that I study Engineering on my spare time is relevant. Except that it means that I have knowledge about EM-field theory and high frequency technique, from other sources than wikipedia.
I have also PMed a mod and asked for the thread to be deleted since nothing new has been discussed and I feel that leaving info about how to create parts of this kind of control system could be dangerous. It was not what I intended when I created the thread. I wanted to discuss the specific switch pack mentioned in the first post, we never did that. Now everybody are at a foul mood instead. I'm sorry for that.
I have also PMed a mod and asked for the thread to be deleted since nothing new has been discussed and I feel that leaving info about how to create parts of this kind of control system could be dangerous. It was not what I intended when I created the thread. I wanted to discuss the specific switch pack mentioned in the first post, we never did that. Now everybody are at a foul mood instead. I'm sorry for that.
DuckJordan
Touring IATSE Member
Not foul mood, just don't like being told how my venue operates. Now I'd love to see the switch pack used in a non pyro. Such as a moving dragon head (shrek comes to mind) and other things that may need DMX to control specific functions. If it deals with peoples safety though I wouldn't use DMX for such things.
MarshallPope
Well-Known Member
Just for conversation, what would be the difference in having a GO button to fire a pyro shot (CO2, Kabuki, et. al.) manually and having someone on a deadman for the couple of seconds surrounding the time needed for the shot to be fired via DMX, for the sake of timing? Maybe with an indicator light to ensure that something hadn't gone horribly wrong and the DMX channel wasn't parked on or something when the deadman was activated?
It just seems to me that the actual method used to trigger the effect isn't as important as the safeties in place allowing the effect to happen.
It just seems to me that the actual method used to trigger the effect isn't as important as the safeties in place allowing the effect to happen.
DuckJordan
Touring IATSE Member
The problem comes in the fact that DMX is very non error checking. Sure it could work for a single piece of pyro, but when you have a rig of 200 - 300 different pyro shots. It becomes more apparent why DMX is not a good solution. Would you need a dead man switch for each pyro piece? or would you put it at the start of the line? or maybe you have three different sends going to three different places where would you put the dead man switch?
I still prefer the old 12 volt system I used for our events. Very reliable, no way to accidentally fire anything. And no way to fire off in the wrong order. While we have used a cue light system to fire pyro...
I still prefer the old 12 volt system I used for our events. Very reliable, no way to accidentally fire anything. And no way to fire off in the wrong order. While we have used a cue light system to fire pyro...
I think this thread deserves to stay, as it shows how adamant many of us are when it comes to DMX controlled Pyro!
DMX should never be used to control anything that will cause bodily harm without a deadman switch at that location.
As has been stated by many others, DMX has no error checking at all.
I assume you know how DMX works, but I saw a great analogy on another bbs,
(And I greatly wish I remember who said it)
DMX is like this,
There is a man standing on the corner, and he says "ready" then starts yelling numbers down the hall.
000
000
128
255
255
etc, etc, a total of 512 times.
Then he says "ready" and then repeats the process, up to 44 times per second.
At no point does he listen back for a response if a command has been received.
There are far to many variables with DMX to use it for pyro.
The only way I would ever consider it is with a dead man switch near every position, with "knowledgeable person" standing next to it.
In any case, no fowl mood either, just adamant about safety.
DMX should never be used to control anything that will cause bodily harm without a deadman switch at that location.
As has been stated by many others, DMX has no error checking at all.
I assume you know how DMX works, but I saw a great analogy on another bbs,
(And I greatly wish I remember who said it)
DMX is like this,
There is a man standing on the corner, and he says "ready" then starts yelling numbers down the hall.
000
000
128
255
255
etc, etc, a total of 512 times.
Then he says "ready" and then repeats the process, up to 44 times per second.
At no point does he listen back for a response if a command has been received.
There are far to many variables with DMX to use it for pyro.
The only way I would ever consider it is with a dead man switch near every position, with "knowledgeable person" standing next to it.
In any case, no fowl mood either, just adamant about safety.
First!
Why In HELL would you fire anything or do anything else that MIGHT harm someone WITHOUT a dead mans switch at that location!!!
If you think that having "a dedicated controller" means you can skip that part you are RISKING PEOPLES LIVES!
Maybe this is why we get stuck! I take all these precations for granted, since I have a background in pyro and you in ligh
Ok, if we are too continue we have to clear out the terminology.
Pyro: A pyro effect is fired(most often) by an e-match. "It caries it's own oxygen with it", meaning it can fire in vacuum. Stage Flames and CO2 is not part of this category.
Flames: Flame effects are often propane or a pressurised alcohol. They are released with a solenoid valve and ignited by a pilot flame or a spark when mixed with air("It DOESN'T caries it's own oxygen with it"). Pay attention to the solenoid part.(Not Pyro)
CO2 Jets: CO2 released through a solenoid valve.(Not Pyro)
It is not only I that differ between pyro and flames, take a look at stricktly fx's homepage for example.
DuckJordan Mentiond the number 300. That is most likely pyro effects we are talking about. Since a pyro effect can only be fired once. There are a lot of systems out there for firing pyro.
LET US DROP PYRO CONTROLLERS. Dmx is totally worthless for pyro! Nobody is suggesting using DMX for pyro(see rough definition above).
Moving on too the effects at hand!
Those relevant to look at are those who for example use a solenoid(for example flames)! They can be fired several times, and you extremely seldom have 300 flame units at an event. These CAN NOT in a good way be fired by any pyro controllers, since part of the effect is deciding how long it should be on. This makes it(controller wise) more like a light than pyro. In pyro you have one contact for every cue! If you have 3000 cues in your show you need to have 3000 contacts to make it happen. There is no problem to have 3000 cues(every blink in a chase is a cue) with 10 Par-lights, or flames for that matter.
Do I need to explain that part further or can we drop pyro and move on too flames and other machinery.
I know how DMX works, I know that the reflections come from bad impedance matching and so on and so forth.
Now take a look at MarshallPopes post above.
What happens when you send bad DMX to a reciver that does not got any power? Nothing!
What happens when you get a short circuit in a analog controller? When you arm it to fire, the short circuit fires as soon as it is armed!
You can have errors in the most simple analogue system as well, that is why you do not arm until ready to fire!
Why In HELL would you fire anything or do anything else that MIGHT harm someone WITHOUT a dead mans switch at that location!!!
If you think that having "a dedicated controller" means you can skip that part you are RISKING PEOPLES LIVES!
Maybe this is why we get stuck! I take all these precations for granted, since I have a background in pyro and you in ligh
Ok, if we are too continue we have to clear out the terminology.
Pyro: A pyro effect is fired(most often) by an e-match. "It caries it's own oxygen with it", meaning it can fire in vacuum. Stage Flames and CO2 is not part of this category.
Flames: Flame effects are often propane or a pressurised alcohol. They are released with a solenoid valve and ignited by a pilot flame or a spark when mixed with air("It DOESN'T caries it's own oxygen with it"). Pay attention to the solenoid part.(Not Pyro)
CO2 Jets: CO2 released through a solenoid valve.(Not Pyro)
It is not only I that differ between pyro and flames, take a look at stricktly fx's homepage for example.
DuckJordan Mentiond the number 300. That is most likely pyro effects we are talking about. Since a pyro effect can only be fired once. There are a lot of systems out there for firing pyro.
LET US DROP PYRO CONTROLLERS. Dmx is totally worthless for pyro! Nobody is suggesting using DMX for pyro(see rough definition above).
Moving on too the effects at hand!
Those relevant to look at are those who for example use a solenoid(for example flames)! They can be fired several times, and you extremely seldom have 300 flame units at an event. These CAN NOT in a good way be fired by any pyro controllers, since part of the effect is deciding how long it should be on. This makes it(controller wise) more like a light than pyro. In pyro you have one contact for every cue! If you have 3000 cues in your show you need to have 3000 contacts to make it happen. There is no problem to have 3000 cues(every blink in a chase is a cue) with 10 Par-lights, or flames for that matter.
Do I need to explain that part further or can we drop pyro and move on too flames and other machinery.
I know how DMX works, I know that the reflections come from bad impedance matching and so on and so forth.
Now take a look at MarshallPopes post above.
What happens when you send bad DMX to a reciver that does not got any power? Nothing!
What happens when you get a short circuit in a analog controller? When you arm it to fire, the short circuit fires as soon as it is armed!
You can have errors in the most simple analogue system as well, that is why you do not arm until ready to fire!
I don't think it is all that far fetched to have some kind of noise or signal reflection to get read as a certain value for three seconds. "Kind of undoable" is not the same an impossible. Many performance venues have just the kind of electromagnetic environment to make the slightly possible happen, even if you can't in the lab.
The use of DMX in this way also implies that a microprocessor has the final say in when something detonates. A microprocessor should never be given that level of autonomy because it is too easy for one to go to la la land from a little signal glitch or supply rail sag. There needs be a mechanical switch or a mechanical switch controlling a relay that breaks the circuit to the firing device. Anything else is just asking for an accident. Switches aren't perfect either, but they are about a thousand percent more reliable than any microprocessor based circuit. You can always have a microprocessor making decisions ahead of the switch, but the switch should have the final vote on firing. That's my humble opinion from my 25 years of electronics experience and a BSEET degree.
DuckJordan
Touring IATSE Member
Fine, CO2 is fine, flame on the other hand NO, CO2 can be safely turned off at close distance, flame on the other hand not so much. Sorry santai for being a little lost on termonology, but for the sake of the education portion of this forum, Any kind of special effect that involves any discharging from a valve, hole, table, or any other such device including bot not limited to, Confetti, CO2, flame, Pyro, air cannon, streamers, or loud bang effects, Is considered at least in my venues and my county as well as the neighboring counties to be considered "Pyrotechnic effects" under the legal term. Any and all "Pyrotechnic effects" must be approved by both the fire marshal, and myself to be able to use them. The only effect I would consider to be allowable to be fired from a DMX system would be CO2.
Those are also the most common errors found with DMX, I've seen controllers send completely wrong data (Not reflections or a short) but bad data from the controller. errors are easier diagnosed and solved on an analogue system than a digital system. When I put peoples lives in danger by deciding to use a system never intended for use by Pyrotechnicians I am no better than a military general who authorizes chemical warfare on a populace.
Those are also the most common errors found with DMX, I've seen controllers send completely wrong data (Not reflections or a short) but bad data from the controller. errors are easier diagnosed and solved on an analogue system than a digital system. When I put peoples lives in danger by deciding to use a system never intended for use by Pyrotechnicians I am no better than a military general who authorizes chemical warfare on a populace.
@FMEng
Additionally, a microprocessor may be quite stable itself, but the code running on it may make improper assumptions, and there's no real way to for a user to determine if it does or not without extensive testing - or by using it until something goes wrong. Nothing against the company that's selling this, but they aren't exactly Boeing or QNX.
I wouldn't have any qualms with using this for standard DMX purposes, but when it's attached to something imminently dangerous, I'd rather have a setup designed with safety first and DMX control second, not the other way around.
Additionally, a microprocessor may be quite stable itself, but the code running on it may make improper assumptions, and there's no real way to for a user to determine if it does or not without extensive testing - or by using it until something goes wrong. Nothing against the company that's selling this, but they aren't exactly Boeing or QNX.
I wouldn't have any qualms with using this for standard DMX purposes, but when it's attached to something imminently dangerous, I'd rather have a setup designed with safety first and DMX control second, not the other way around.
There are a lot of misunderstandings in this thread. Please, let's all be rational in our posts and not get heated (pun intended).
We must not always assume that someone who lists being a student is someone early in their career. Just as we cannot assume that someone who lists themselves as a professional in some manner is a seasoned technician. You will learn if you pay attention to the posts over a long period of time who fits which category (especially if you paid attention when the person originally joined the forum, if you were here then).
We do base our judgement on our past experiences, unfortunately not many of us have qualified experience in this topic. This is the reason that it was verboten for a long time on the forum.
This is an international forum and some terminology and the way things are handled are quite different from region to region. It is always good to know where someone is coming from (if they will kindly share that information) so you may understand that communication may be a little difficult. As stated, many people do not stick to strict definitions for pyro (even the AHJs) and will consider anything that creates flame or smoke to fall within the same naming category.
So, all of that being said, I do in fact work in a professional environment where DMX is used as the control mechanism (not the safety mechanism) for special effects including many types of "pyro" (gerbs of various sorts, aerials, flame generators, foggers). I cannot and will not discuss any other portion of the system as I am neither qualified to do so, nor would my confidentiality agreement with my employer allow me to do so.
The safety mechanisms are the important part of any system. Human error can come into play in any system as well as electrical/mechanical failures. It is the system design that prevents us from harm in general. So, we can either go about ignoring the DMX portion of this thread and move along to the intention of discussing the quality of a safety device or we can close the thread. However, I do think that those who can only speculate should not offer their opinions as definitives. Since this is a dangerous topic, we need to have serious discussion on the matter.
We must not always assume that someone who lists being a student is someone early in their career. Just as we cannot assume that someone who lists themselves as a professional in some manner is a seasoned technician. You will learn if you pay attention to the posts over a long period of time who fits which category (especially if you paid attention when the person originally joined the forum, if you were here then).
We do base our judgement on our past experiences, unfortunately not many of us have qualified experience in this topic. This is the reason that it was verboten for a long time on the forum.
This is an international forum and some terminology and the way things are handled are quite different from region to region. It is always good to know where someone is coming from (if they will kindly share that information) so you may understand that communication may be a little difficult. As stated, many people do not stick to strict definitions for pyro (even the AHJs) and will consider anything that creates flame or smoke to fall within the same naming category.
So, all of that being said, I do in fact work in a professional environment where DMX is used as the control mechanism (not the safety mechanism) for special effects including many types of "pyro" (gerbs of various sorts, aerials, flame generators, foggers). I cannot and will not discuss any other portion of the system as I am neither qualified to do so, nor would my confidentiality agreement with my employer allow me to do so.
The safety mechanisms are the important part of any system. Human error can come into play in any system as well as electrical/mechanical failures. It is the system design that prevents us from harm in general. So, we can either go about ignoring the DMX portion of this thread and move along to the intention of discussing the quality of a safety device or we can close the thread. However, I do think that those who can only speculate should not offer their opinions as definitives. Since this is a dangerous topic, we need to have serious discussion on the matter.
Going back to your original post SanTai,
I believe the safety channel is nearly completely worthless, and imbibes the user with a dangerous false sense of security.
I know you feel we have been somewhat harsh with you about the use of "Common Sense" But on an online bulletin board, the amount of common sense available is not known. Plus, when dealing in an online forum, who knows how much common sense the next person that reads it has. I often say the obvious because it is not obvious to everyone that might read this post 2 years later.
In any case, I would not use that switch pack for anything that could cause injury, as I don't believe it comes close to adding enough safety to the system.
Peace,
I believe the safety channel is nearly completely worthless, and imbibes the user with a dangerous false sense of security.
I know you feel we have been somewhat harsh with you about the use of "Common Sense" But on an online bulletin board, the amount of common sense available is not known. Plus, when dealing in an online forum, who knows how much common sense the next person that reads it has. I often say the obvious because it is not obvious to everyone that might read this post 2 years later.
In any case, I would not use that switch pack for anything that could cause injury, as I don't believe it comes close to adding enough safety to the system.
Peace,
Last edited:
DuckJordan
Touring IATSE Member
to look back on it, this device requires a certain DMX signal and level to be sent to it for it to arm. Whats the difference between a parked channel (at the right value) or recorded into a cue? While that may work great for arming at that cue you aren't providing any safety to the effect. Your operator of your console who may or may not be educated in the effect is now deciding whether its safe or not to fire? As an LD I wouldn't want to have to worry about anything other than lights for a production. Let alone an intensive pyrotechnics or flame effect.
Duck, I think that you have missed some crucial information here. The LD would never be responsible for these types of special effects. This would be handled by a separate console dedicated for the purpose of special effects, separate from the lighting network. Yes, the operator could bypass the safety device by parking the channel, and then that person would get fired. Pyrotechnics and other special effects like this do not have the ability to cut corners.
If you are worried about this, then that is your right to deny an event using this into your space. You have stated that you have experience with analog type systems for pyrotechnics, but do not have experience with many of the other effects which cannot run on an analog system. So, as someone who has jurisdiction over a space (as you seem to have by your claims), then you should probably put it in your facility guidelines that any pyrotechnic effect controlled by DMX will not be allowed into the facility, no matter any other safety precautions, so that you will not need to worry about production companies bringing this into your space. As TD of a roadhouse, our facility had to have a blanket ban on all pyrotechnic effects, so I know how this can affect business. At the same time, I did not have to worry if I did not have appropriate experience in the matter.
If you are worried about this, then that is your right to deny an event using this into your space. You have stated that you have experience with analog type systems for pyrotechnics, but do not have experience with many of the other effects which cannot run on an analog system. So, as someone who has jurisdiction over a space (as you seem to have by your claims), then you should probably put it in your facility guidelines that any pyrotechnic effect controlled by DMX will not be allowed into the facility, no matter any other safety precautions, so that you will not need to worry about production companies bringing this into your space. As TD of a roadhouse, our facility had to have a blanket ban on all pyrotechnic effects, so I know how this can affect business. At the same time, I did not have to worry if I did not have appropriate experience in the matter.
DuckJordan
Touring IATSE Member
It's stated in our tech packet and known to potential users of our facility id love to learn more as that's the best I can do. If at some point I can become more familiar with the digital systems and the safeties in place I would consider removing the ban on a case to case basis. So i would like to see this discussion continue. It was never my intent to end this discusion or be closed minded about it. I just would prefer more info of this claimed safe use of dmx.
How different product adds safeties to their operation, check with the manufacturer/manual. For custom made effects such as certain flames, check with the company in question. How it is implemented and what extra is added, check with the company firing the effect.
I am not going to go into more detail how a theoretical system could be built or those I have seen are setup.
The reason the standard answer is "call a pro" is that you never have a inexperienced person doing pyro.
Assuming the safety channel works, what are the rest of risks of failure of the product.
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