Shoot holes in my estop idea

Time for me to work on filing CDRH stuff.

Want to build an estop system.

My plans are to mount my FB4 DACs in a box. Each box will contain the FB4 DAC, a 12v PSU, powercon input that powers the 12v PSU for the FB4 and also feeds a PCB with a power cut relay. Ethernet input for estop. Powercon output and DB25 output to the projector.

I will run 100mbps network. There are two extra pairs of wires not used. On gigabit, each pair goes to magnetics for that networking standard so I will use one lead from one for GND and one for 5v.

My board (powered by the 12v supply in the DAC box) will have an op-amp and resistor for bringing in 5v and powering the op amp, then the needed crap for a relay that feeds projector.

I will use high speed photography to measure the output drop on projector when power cut is initiated to show the output loss is super rapid (Lightspace Plutos IIs, it' so quick it's not funny.)

I know XLaser does something similar but not sure the details. When I was younger we used to dump dual 100mbps ethernet on single cat5 and 100mbps + ISDN PBX phone and other craziness in our nerd house.

I plan to get auto MDX/MDI switches (low end) and bind all those extra pins together for the stop thing.

Will keep it isolated to avoid ground loops.

Any issues that come to mind? Key triggered stop plunger will supply 5vdc.

Was thinking maybe AC is better due to less line loss?

Maybe a few boxes for FB3 projectors but really I hate anything that isn't ethernet.

Are you basically saying you are going to have a relay that is powered from 5v?
Well, after a second look, sounds like 5v just controls your circuit and the circuit controls the relay?
Any chance the circuit is not failsafe?

How about using a opto-isolator to turn your relay on/off? Something like MIDI, however MIDI uses a current loop.

Also in the switch you will be connecting the estop wires together (bypassing the transformers)? That is what I think you are doing from what you have written.

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Originally Posted by cfavreau

How about using a opto-isolator to turn your relay on/off? Something like MIDI, however MIDI uses a current loop.

Also in the switch you will be connecting the estop wires together (bypassing the transformers)? That is what I think you are doing from what you have written.

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Crap I said op amp I meant opto isolator above. Just that and a 330 ohm resistor or something is what I figure.

Estop plunger provides power to all devices, then the rest is just receive…. Line voltage drop could be an issue? Dunno.

Do the Plutos have any eStop capability already? Sounds like a good plan. I think the only other things would be protection like reverse polarity (diode), overvoltage (zener diode?), a current limiting resistor (I think that is what you described already) and then a pull down on it so that if there is no connection it is off. You could use a differential receiver and I think those are low output if nothing is connected.

two twenty ma current loops. One Estop sent out , One Interlock sent back, run it off 12 or better 24V isolated, and use these modern 20 mA led current source chips in a 3 pin package. 3 conductors of an ethernet cable are used.
Current mode ignores noise in a club, stage, or cell tower environment. Each projector has two optos, one in, one out. socket the optos, use a 9$ isolated psu module for the hot side of the interlock in the projector, so you have 2 to 4 Kilovolt isolation between interlock / estop and projector electronics. standardize it and make it open source.

Parts cost, dirt cheap...
Reliability, well industry uses 4-20 mA for safety of life controls for a reason. Distance it can go? What half a mile or more...

optos are either on or off, and have protection diodes on them to prevent reverse current. The loop has a series diode and a 150 mA fuse to prevent nasties of noobie wiring.

In theory, you only need 3 wires, to increase simplicity and reliability a bit, I'd use four.

Steve

Here is the other thread,

https://photonlexicon.com/forums/sho...able-projector

At a Vf of 1.6 volts, with a 24V supply, for a typical led in an opto, that is 14 or so projectors on one loop.

The led current limiter chips are 80 cents each, come in a 3 pin TO82 or similar package.

If you need to bypass or test the Estop, 9V battery and a 470 ohm resistor is good for 15 hours of use.

NO current returned to button box = Interlock open. If the Current returned, good to go, interlocks closed and all projectors have power on.
Current on = estop line enables projector shutter etc. No current =no output. If projectors have a key , it is on ESTOP line inside projector, not on the outside, isolated loop.

Front to back Isolation is needed in a pro environment, hence the little floating psu brick.

If you look at the other fellows post, he chose 3 pins on the ethernet connector unlikely to have a conflict. I'd rather use a hirose or mini-xlr rather then ethernet cable for the daisy chain to be professional.

Current Loops, not voltage loops.

Easy enough to add another led in series with the loop as a indicator, too.

I've been wanting to do this for years, with a current loop.

If you use a set of relay contacts in the projector for the interlock loop, it is even cleaner then the optocoupler route. Relay closed = interlock good in projector.

Steve

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Originally Posted by telmnstr

Time for me to work on filing CDRH stuff.

Want to build an estop system.

My plans are to mount my FB4 DACs in a box. Each box will contain the FB4 DAC, a 12v PSU, powercon input that powers the 12v PSU for the FB4 and also feeds a PCB with a power cut relay. Ethernet input for estop. Powercon output and DB25 output to the projector.

I will run 100mbps network. There are two extra pairs of wires not used. On gigabit, each pair goes to magnetics for that networking standard so I will use one lead from one for GND and one for 5v.

My board (powered by the 12v supply in the DAC box) will have an op-amp and resistor for bringing in 5v and powering the op amp, then the needed crap for a relay that feeds projector.

I will use high speed photography to measure the output drop on projector when power cut is initiated to show the output loss is super rapid (Lightspace Plutos IIs, it' so quick it's not funny.)

I know XLaser does something similar but not sure the details. When I was younger we used to dump dual 100mbps ethernet on single cat5 and 100mbps + ISDN PBX phone and other craziness in our nerd house.

I plan to get auto MDX/MDI switches (low end) and bind all those extra pins together for the stop thing.

Will keep it isolated to avoid ground loops.

Any issues that come to mind? Key triggered stop plunger will supply 5vdc.

Was thinking maybe AC is better due to less line loss?

Maybe a few boxes for FB3 projectors but really I hate anything that isn't ethernet.

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a large heavy plate in front of the projector suspended by a string backed by a steel plate. A sharp knife mounted so all you do is hit a button and the string is cut. No power full proof. Yes I’m kidding

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Originally Posted by telmnstr

Time for me to work on filing CDRH stuff.

Want to build an estop system.

My plans are to mount my FB4 DACs in a box. Each box will contain the FB4 DAC, a 12v PSU, powercon input that powers the 12v PSU for the FB4 and also feeds a PCB with a power cut relay. Ethernet input for estop. Powercon output and DB25 output to the projector.

I will run 100mbps network. There are two extra pairs of wires not used. On gigabit, each pair goes to magnetics for that networking standard so I will use one lead from one for GND and one for 5v.

My board (powered by the 12v supply in the DAC box) will have an op-amp and resistor for bringing in 5v and powering the op amp, then the needed crap for a relay that feeds projector.

I will use high speed photography to measure the output drop on projector when power cut is initiated to show the output loss is super rapid (Lightspace Plutos IIs, it' so quick it's not funny.)

I know XLaser does something similar but not sure the details. When I was younger we used to dump dual 100mbps ethernet on single cat5 and 100mbps + ISDN PBX phone and other craziness in our nerd house.

I plan to get auto MDX/MDI switches (low end) and bind all those extra pins together for the stop thing.

Will keep it isolated to avoid ground loops.

Any issues that come to mind? Key triggered stop plunger will supply 5vdc.

Was thinking maybe AC is better due to less line loss?

Maybe a few boxes for FB3 projectors but really I hate anything that isn't ethernet.

---

a large heavy plate in front of the projector suspended by a string backed by a steel plate. A sharp knife mounted so all you do is hit a button and the string is cut. No power full proof. Yes I’m kidding

He said shoot holes, not Guillotine..
Steve

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a large heavy plate in front of the projector suspended by a string backed by a steel plate. A sharp knife mounted so all you do is hit a button and the string is cut. No power full proof. Yes I’m kidding[/QUOTE]

Sorry I'm so late to this party...

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Originally Posted by telmnstr

Estop plunger provides power to all devices

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2 Caveats:

1) You need 2 separate attenuation methods that are both activated by your e-stop. However, interrupting the AC power supply to the projector is not an approved attenuation method. You are allowed to interrupt the DC supply to the laser diode drivers, however. Other options include a shutter, and crowbarring the modulation inputs to ground.

2) The e-stop circuit needs a separate "start" switch that is separate from the mushroom switch, such that even when all interlock conditions have been satisfied and the e-stop switch has been reset, the circuit will remain in the shutdown state until commanded to restart by the operator. (This prevents unintentional projector restarts following a momentary loss of power, or momentary connectivity loss through the cabling of the interlock circuit.)

Number 2 is the tough one. To be compliant, you must be able to unplug any cable (control, data, power, e-stop), anywhere between front of house and the projector, and the projector must immediately shut off, *AND*, when the cable is plugged back in, the projector must remain in the shutdown state until the "start" button is pressed again.

Essentially, this means you need a latching relay inside each projector.

Adam

PS: If you are only doing this for a class 3B laser, you can ignore #2, but if you're going to use this on any class 4 lasers, then #2 applies.

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Originally Posted by buffo

Sorry I'm so late to this party...

2 Caveats:

1) You need 2 separate attenuation methods that are both activated by your e-stop. However, interrupting the AC power supply to the projector is not an approved attenuation method. You are allowed to interrupt the DC supply to the laser diode drivers, however. Other options include a shutter, and crowbarring the modulation inputs to ground.

2) The e-stop circuit needs a separate "start" switch that is separate from the mushroom switch, such that even when all interlock conditions have been satisfied and the e-stop switch has been reset, the circuit will remain in the shutdown state until commanded to restart by the operator. (This prevents unintentional projector restarts following a momentary loss of power, or momentary connectivity loss through the cabling of the interlock circuit.)

Number 2 is the tough one. To be compliant, you must be able to unplug any cable (control, data, power, e-stop), anywhere between front of house and the projector, and the projector must immediately shut off, *AND*, when the cable is plugged back in, the projector must remain in the shutdown state until the "start" button is pressed again.

Essentially, this means you need a latching relay inside each projector.

Adam

PS: If you are only doing this for a class 3B laser, you can ignore #2, but if you're going to use this on any class 4 lasers, then #2 applies.

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Hmmm. Do the current projectors being sold that meet all these requirements really meet all these requirements?

What kind of reaction time does it require to satisfy the eStop stuff? Challenge/response over ethernet valid? Might as well move it all to ESP32 or something run it on the same switches driving the FB4s.

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Originally Posted by telmnstr

Hmmm. Do the current projectors being sold that meet all these requirements really meet all these requirements?

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I can only speak for X-Laser projectors, as I have done *lots* of pre-show checks with those to verify proper operation of the interlock system.

For those projectors, yes, they really do meet all these requirements. Their remote E-stops have a separate run button that must be pressed each time you want to "start" a projector. If you unplug any cable, the projector will shut down and stay shut down even after you plug the cable back in.

While I've had the opportunity to play with other brands of projectors at various get-togethers over the years, I don't recall specifically testing the class IV reset on any of them. (Well, with the exception of a few projector brands that were clearly NOT compliant {cough} LASWERWOLD {cough} as they were lacking in several areas, of which the class IV reset was just one of many deficiencies that were plainly obvious.)

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What kind of reaction time does it require to satisfy the eStop stuff?

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Not sure there is a published specification, to be honest. I would guess that anything on the order of a tenth of a second or faster should suffice. (Especially since the limiting factor may well be the speed of the mechanical shutter, or the speed of the mechanical relay.) Of course, a solid-state relay would be much faster, but I've seen plenty of certified projectors that use mechanical relays (and even some that used Ledex rotary solenoids for shutters).

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Challenge/response over ethernet valid?

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So long as you preserve the functionality of the class IV reset (total shutdown on loss of communication, and no auto-restart upon resumption of communication unless you receive a separate operator command to restart), I don't see any reason why you couldn't do E-stop over Ethernet. Figure that if you don't get a response within some short window (10 milliseconds? 50 milliseconds? something in that range...), you trigger an e-stop condition.

That being said, I'm pretty sure the X-Laser solution is hard-wired, even though they use Ethernet cable to connect everything. I seem to recall that they only use 4 wires in the ethernet cable for data, which leaves them with 4 wires for their interlock circuit. Although I also remember them talking about how they use the Mercury controller to implement E-stop on all projectors that have Mercury built-in, so maybe they are planning to move away from the hard-wired solution as they incorporate Mercury into more of their product line...

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Might as well move it all to ESP32 or something run it on the same switches driving the FB4s.

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Yeah, like using the Mercury controller described above.

Adam

Lots of great info in this thread around e-stopping in a way that makes CDRH happy. I'll throw in a shameless plug for Stanwax's ILDA breakout boards which have facilities to easily include an e-stop. Looking at the the stanwax catalogue, it appears that there is one available specifically for FB4's: https://shop.stanwaxlaser.co.uk/ilda...-fb4-632-p.asp

I used stanwax ILDA breakout boards the last time I built a couple of PJ's and including an e-stop was relatively simple: https://www.flickr.com/photos/raytracing/7406362364/

Whatever route you go down, make the e-stop button as large and temptingly shiny as possible (ya know, fer safety!). Here's some human machine interface pr0n: https://eao.com/

Buffo - yea the X-Laser stuff is pretty cool, as I remember they use an ethernet switch IC in projector to split for Mercury, FB4 I'd guess and daisy chain to next projector. Then they used unused wires (100mbps) for e-stop.

Robin - oo nice! I use 3 FB4s (externally.) I wonder if the Stanwax board shunting the output + projector power cut is enough? I see the Stanwax board has the output shunting but I assume you would need either a mech shutter or DC PSU drop?


Going the ethernet route, there are these boards which appear to now be $10,
https://www.cnx-software.com/2020/11...with-ethernet/
And me and ChatGPT could probably make a program to handle doing something like DC power cut (3 x relays) and maybe crowbar the modulation. I would do a SPI OLED screen or something for status/IP and a SPI LCD on the pendant so it could show status. But if Stanwax PCB is less resistance I am all about making things happen easier.

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Originally Posted by telmnstr

I wonder if the Stanwax board shunting the output + projector power cut is enough?

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The latest version of the Stanwax board crowbars the modulation lines to ground upon interlock, and also opens the main relay (which is typically used to switch the DC power to the diode drivers). When integrated in this manner, the Stanwax board is fully compliant with the requirements of a class IV reset. Just remember to use the relay to switch the DC power, not the AC power, and you are golden.

Alternately, you could use the relay to control a mechanical shutter. But you can also use the shutter signal on the output of the Stanwax board to control a shutter, since that signal will also be crowbarred to ground upon interlock.

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If the Stanwax PCB is less resistance I am all about making things happen easier.

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The main reason I incorporated the Stanwax board in my product report (as opposed to designing my own circuit) is that I was informed by Casey Stack that the CDRH was already familiar with the Stanwax board and they very much approved of its use. That meant they would be far less likely to ask a bunch of follow up questions about my interlock scheme.

Rob has a nice cut sheet that explains the features of the board, and I included that document in my product report, along with a block diagram that showed how it would be integrated with the projector's internal components. It's been almost a decade since I filed that first report, and they've never asked me for any further information. :cool:

Adam