Interlock circuits.

[DMills]

What are people doing for ILDA interlock loop wiring?

I see people splitting ILDA as literal parallel splits which implies that the interlock loop must have something a bit funny happening or that everyone has settled on the same design?

I know what I would like to implement, but it would be useful to know that it will work with other peoples rigs, hence the query.

Regards, Dan.

[mixedgas]

I follow the standard and loop current through mine.

Steve

[DMills]

That bit is obvious.

The question is how much, and from what voltage source, and if we hooked a few lasers in parallel and unplugged the controller would the interlock circuits interact in unfortunate ways?

I can see that a galvanically isolated current source of a few volts compliance and limited to a few ma should be reasonably safe (until the other laser has the same thing with opposite polarity!)....

Regards, Dan.

[slicklasers]

I use a db15 connector and jumper pins 1 and 2 and then I have another 13 pins to use for extra effects.

[shrad]

for what I know, aren't standard interlock current and voltage ratings 15mA 12V DC?

[Doc]

for what I know, aren't standard interlock current and voltage ratings 15mA 12V DC?

I believe what Dan is refering to is the fact that a second or third projector in a chain could provide a ground or signal that would in effect maintain the loop even if for instance the DAC was unplugged or the loop otherwise intentionally broken, thereby rendering it useless.

Either that or projector #1 possibly shorting out projector #2

Either of these two scenarios are possible without a clear and rigid wiring scheme or isolation of the interlock loop at any splitter or junction box.

[mixedgas]

I'm 12V, about 100 mA. Current comes from the projector.

Steve

[mccarrot]

Pin 4 and 17 must connected together when the interlock (DAC + ILDA cable) is connected. In some of my previous designs of a remote interlock I din't do this but this will give problems with lasers with DMX boards in the lasers, as some DMX boards like spacelas will check for the 4 % 17 shortcut else the board will go in autoplay mode.

After a year and about 20 revisions later I think I now have the ultimate (EN60825-1 complient) remote interlock circuit finished.

here is a photo of the prototype:

[Doc]

My projector also conforms to the EN60825-1 standard, however it is still theoretically possible that if it was to be connected to another projector that didn't match the scheme; the other projector could maintain the ground signal with the DAC out of loop.

In other words; there should be a hard and fast rule about polarity, current and voltage.

QUOTE=mccarrot;128774]Pin 4 and 17 must connected together when the interlock (DAC + ILDA cable) is connected. In some of my previous designs of a remote interlock I din't do this but this will give problems with lasers with DMX boards in the lasers, as some DMX boards like spacelas will check for the 4 % 17 shortcut else the board will go in autoplay mode.

After a year and about 20 revisions later I think I now have the ultimate (EN60825-1 complient) remote interlock circuit finished.

here is a photo of the prototype:[/QUOTE]

[DMills]

Actually, the rule should probably be that when you provide an ILDA loop out, it must have a dry set of contacts driven by your interlock loop circuit, such that it appears to be a controller to the downstream device.

Just paralleling ILDA is not really ever a safe thing to do.

Here is what I have been using, with a loop out (where fitted) being driven by a second set of contacts on the relay.

And yes, it was the interaction of multiple projectors in parallel that was bothering me (I don't think it should ever be done without some logic in the way).

Regards, Dan.