Laser emergency stop over ethernet

[loopee]

So how are you going to wire up the kill switch for additional projectors, you’re going to have to loop in and out of every switch port and either always use all switch ports or some kind of loop plug

The other issue is that you'll potentially will be passing 24 volts DC along 600 meters of Cat5 cabling (based on the 6 port switch you have shown) and will have considerable volt drop across that length of cable.

This also then leads to the blown Christmas tree bulb syndrome of trying to identify which link is a fault when you have a dodgy cable

Another issue is, are you going to standardise the projectors all to be the same, each with a connection to the 24volt power supply of the scanners?
Don’t think the power supplies will appreciate that, and also Power hum here we come!

So why not put the key switch and emergency stop inline and use the single power supply of the switch/hub and parallel the blue and brown conductors to minimise the volt drop, then use one relay in the projector to control the lasers and the QM.net board and Shutter.

However I do think that by the time you get to five relays (and medium sized ones at that) the voltage drop is going to be an issue unless you use something like opto couplers to control them.

One more suggestion would be to combine the safety stop box and switch into one unit

[sugeek]

Good Day,

Not trying to get off track, just a idea/question. PoE may actually be good solution if you get a switch with PoE support then get rid of the AC portion there and it would open up another set of fun stuff... If we want to go down that road I can babble more.

-Adam

[keeperx]

PoE uses phantom power so you will not lose a data pair.

[loopee]

PoE uses phantom power so you will not lose a data pair.

Not always the case, some vendors have a pre-standard prior to 802.11af that only uses the spare pairs that are not used for data transmission.

All the devices that have pre-standard PoE are only 100Base-T devices

Cisco’s current line of PoE switches will support both standards for legacy product support and I don’t think they are the only ones.

However in this case it’s not doing PoE, it’s purely putting 12V and 24V down the spare un-used pairs

[keeperx]

yeah i was talking EEE 802.3-2008
but since POE can handle 48v at 400mA steady with like 15W burst (i think that right) then powering the dac over ethernet should work just fine..

maybe pangolin should think about adding that to the dac so its plug and play...

[mccarrot]

quote=loopee So how are you going to wire up the kill switch for additional projectors, you’re going to have to loop in and out of every switch port and either always use all switch ports or some kind of loop plug

MCCarrot:
I allready have a switch build in a box and on the box there are also Neutrik RJ45 connectors, those connectors are very strong. From Neutrik plug I wire pair 1 & 2 to the switch and all blues and browns to each other.

The other issue is that you'll potentially will be passing 24 volts DC along 600 meters of Cat5 cabling (based on the 6 port switch you have shown) and will have considerable volt drop across that length of cable.

From your laptop/safety to the switch on the stage can be maximum 100 meter.
On stage you can again put your lasers again 100 meters away from your witch. So the theoretical max lenght will be 200 meters. But I have never seen a Stage 200meter width. you???


This also then leads to the blown Christmas tree bulb syndrome of trying to identify which link is a fault when you have a dodgy cable

No. Or you have 2 wires to your projector, cat5 for QM.net and another cable for the safety switch or you have only 1 cable you can break. so you need to bring 2 different spare cables instead of 1.

Another issue is, are you going to standardise the projectors all to be the same, each with a connection to the 24volt power supply of the scanners?
Don’t think the power supplies will appreciate that, and also Power hum here we come!

Hmmm yes, this is something we have to think about...

So why not put the key switch and emergency stop inline and use the single power supply of the switch/hub and parallel the blue and brown conductors to minimise the volt drop, then use one relay in the projector to control the lasers and the QM.net board and Shutter.

Then you can not setup and test all the QM's and Lasers without laseroutput. and also when I turnoff the QM together with my lasers I get a very short output of laserbeams from my projectors, so it's always good to turn off your lasers first before you switch off your QM.net

However I do think that by the time you get to five relays (and medium sized ones at that) the voltage drop is going to be an issue unless you use something like opto couplers to control them.

The standard 24V DIN rails relais I now have are 600ohm, Cat5 got max 0,188 ohm/meter resistance, so with Worstcase 200 meter cable the DC resistance is max 75Ohm. With 75 ohms you have 2.6V voltage drop, but with allot more relais you defenitly wil have a problem, so I think it's better to use Electronic relais instead, to keep the current as low as possible.

One more suggestion would be to combine the safety stop box and switch into one unit

And wire Multiple wires from the safety to the projectors? If you are at a rave and the stage is 100 meter away from the point you are controlling you have to Carry allot of Cat5 with you instead of just 1 cable to the swith on stage close to the lasers.

[aijii]

Excuse me guys, couple of sanity checks here...

Firstly, proper (when i say proper I mean enterprise grade) POE switches will negotiate with the device at the other end before applying full power... I don't think it is a suitable solution here...

Secondly, regarding the talk around using complicated IP based or "packet stream" techniques to determine whether the switch is depressed or not..

Well, as our esteemed colleauge Mr.Benner has asserted multiple times (and i have to agree with him), safety systems should be as risk free as possible.

Forget about using anything "digital or uProc based" to turn a shutter on or off - there is enough digital shit in your controller, enough complicated shit in your projector (scanners, alignment, etc), that there are multiple single points of failure that can result in a dangerous laser emission.

Surely the point of the whole safety shutter emergency switch thing is to provide a rock solid, simple, reliable, fool proof means of dropping a shutter in front of a laser beam...

So why would we do anything more complicated than sending a voltage down a couple of spare conductors in a fast ethernet link to lift a shutter??

Unless the real goal of this excercise is to extend penis sizes... but i thought thats what building bigger and better laser projectors than everyone else was about :P

[sugeek]

Excuse me guys, couple of sanity checks here...

Firstly, proper (when i say proper I mean enterprise grade) POE switches will negotiate with the device at the other end before applying full power... I don't think it is a suitable solution here...

<snip>

Unless the real goal of this excercise is to extend penis sizes... but i thought thats what building bigger and better laser projectors than everyone else was about :P

I was assuming a power injector and an extractor in example: [device]->ethernet->[PoE injector]->[kill switch]->[PoE decoupler]< 1.power 2. ethernet

Thus turn the kill switch it cuts the power to the switch... (but you are right it should also close the shutter) Alot of people here don't think they need a shutter due to the wiring paper by bill suggesting that you can kill the lasers too (I think of this as an in addition to closing the shutter), but people think DPSS lasers don't need them.

I think I am done here!
Adam

[mccarrot]

You have shutters for 5V 12V and 24V, for the diagram it doesn't matter if you use a relais or a shutter in the projector. But then there is a new problem, the 24V shutters take 85mA. so when you connect a couple of lasers to the safety stop the voltage drop will be too high.

[mccarrot]

Revision 2.4