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What's the difference between RS connectors and LCS connectors and what are they used for?

connectors rs LCS

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#1 davide sorasio

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Posted 12 October 2015 - 09:53 AM

What's the difference between RS connectors and LCS connectors and what are they used for?

Thank you so much in advance,

Davide


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#2 Kenny N Suleimanagich

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Posted 12 October 2015 - 10:16 AM

RS is used for things like trigger grips. On the 416 it provides 24v power at a maximum draw of 2 Amps. 

 

LCS is "Lens Control System" - Arri has several models of these (WLCS) and the great advantage of the 416 Plus (and Alexa Plus) is that you can wire up the Focus, Iris, and Zoom motors directly to the camera, which can then communicate wirelessly to the controller (or tethered). 


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#3 davide sorasio

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Posted 12 October 2015 - 10:23 AM

All right, I have a couple more questions related top this. Is the RS port what people commonly referes to "power port"?  and looking at the camera diagram I see that there are also different clm motor connectors, so is the LCS connector an alternative to the CLM connector or is it something I would plug togheter? And one more thing, in which port should I power an onboard TV logic on the ARRI 416?

Thanks so much, you are being really helpful!


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#4 Kenny N Suleimanagich

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Posted 12 October 2015 - 12:06 PM

Not sure of RS being a "power port" but it does provide power. Which CLM monitor connectors are you referring to? 

 

On the IVS there are two female connectors labelled "MM" - meaning Mini Monitor, originally intended to both power and carry video signal to Starlite 4" monitors. You cannot power a monitor through the R/S outputs since you'll create a ground loop and possibly fry the IVS electronics. So you'll need to get a custom cable made (Media Blackout can provide you with one) that connects to the MM connectors (which I believe is a 2-pin LEMO, but you should confirm this with ARRI NY) to your TV Logic. Then run composite/component video through the IVS to your monitor. 

 

Sounds complicated but is very simple. You just need to make sure you have the right cables. The R/S outputs can only power things that won't connect back to the camera (unlike a monitor, but like an LED light or trigger grip). 


Edited by Kenny N Suleimanagich, 12 October 2015 - 12:07 PM.

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#5 davide sorasio

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Posted 12 October 2015 - 12:19 PM

All right, I hope you'll excuse me but I'm facing a language barrier problem now, what do you mean by "The R/S outputs can only power things that won't connect back to the camera"? I cannot understand the meaning of connect back to the camera. And what do you exactly mean by trigger grip? BTW I'm talking about the CLM on the right side of the camera (maybe it's only a 416 PLUS SPEC, I'm trying to atatch the screenshot of the camera manual but the file is too big). Final question, so the 416 was not meant to be connect to on board tv logic when it was created right?

 

Again, THANKS SO MUCH!


Edited by davide sorasio, 12 October 2015 - 12:26 PM.

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#6 Kenny N Suleimanagich

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Posted 12 October 2015 - 12:30 PM

A monitor powered by the RS inputs is also connected to the camera through the BNC at the IVS. So one connection made at RS and the other at BNC - it will cause a ground fault. 

 

Trigger grip looks like this: trigger.jpg

 

The 416 can certainly connect to the TV Logic, but powering it from on-board will require a cable going through the MM connector to avoid ground fault. Call ARRI to confirm the model of this interface, and then you could have one made for your monitor. Otherwise you could just power it with a separate battery system altogether, however inelegant that solution might be. 


Edited by Kenny N Suleimanagich, 12 October 2015 - 12:33 PM.

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#7 Satsuki Murashige

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Posted 12 October 2015 - 12:48 PM

The R/S port is also known as Arri 3pin Fischer and provides 24v power out, as well as the Run/Stop trigger. The R/S function can be used with handgrip triggers, remote triggers, and wireless follow focus motor drivers like the Preston MDR to run and stop the camera remotely from the hand unit.

You can also power 24v devices directly from the port. In order to power 12v devices like a TVLogic on-board monitor, you would need a special cable with a built-in step down transformer to convert and regulate the voltage. If you send 24v power to the 12v monitor, you will damage the monitor.
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#8 Kenny N Suleimanagich

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Posted 12 October 2015 - 12:50 PM

Even with this voltage step-down, it is extremely ill-advised to run monitors from the RS port. The risk of ground fault is high, and the warning light will turn on.
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#9 davide sorasio

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Posted 12 October 2015 - 12:50 PM

All right, things seem to be more clear now. It's that I do not have that much experience with film cameras due to my young age and I could not really figure this IVS thing. One REALLY IMPORTANT clarification I need: what you are saying about the ground loop is also true for digital cameras? So a 3 pin RS port can never power a TV logic? (of course if not with the special cable you are talking about). And which kind of port would I need to power a tv logic on an ALEXA for example? DO I need a Ptap 2 PINS cable?

THANKS SO MUCH,

Davide


Edited by davide sorasio, 12 October 2015 - 12:57 PM.

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#10 Kenny N Suleimanagich

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Posted 12 October 2015 - 12:57 PM

My experience as far as ground fault is limited to the Arri 416. I'm not sure the Alexa would share the problem. Maybe Satsuki can speak to that. 


Edited by Kenny N Suleimanagich, 12 October 2015 - 12:57 PM.

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#11 Satsuki Murashige

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Posted 12 October 2015 - 02:27 PM

No idea about the ground fault, sorry!

Usually in an Alexa package, a TVLogic would be powered with either a 12v Lemo2 connector or d-tap. If this is all going to be a hassle, then why not just put a battery plate on the monitor and run it with Panasonic or Sony BP batteries? Doesn't add much more weight and it is simple.
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#12 Kenny N Suleimanagich

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Posted 12 October 2015 - 02:46 PM

I think the MM output is Lemo2 - that's worth confirming with Arri - since those were designed to power the Transvideo Starlite monitors and in testing I've found it powers others fine. 


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#13 davide sorasio

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Posted 12 October 2015 - 03:04 PM

You guys have been amazing! Thank you so much! in all of this only one thing is still confused to me, and it's electricity related. How does a short circuit happen? and why powering the TV logic from the RS port would create a short circuit? From what I've understood it's because of the 12V vs 24V power output, but in this discussion it has also been mentioned that it might be also because the monitor powerd through the RS port is also conencting back to the camera through the BNC, but isn't it always the case when having on board monitors? Or the problem is due to the different voltage AND the fact that the monitor powered with a wrong voltage would also been connected to the bnc back to the camera?

If I'm not wrong, and please tell if I am when powering a TV logic with a 12v 2 pin power cable the monitor is also connected back to the camera with a BNC right?


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#14 Kenny N Suleimanagich

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Posted 12 October 2015 - 03:14 PM

I'm only speaking from my personal experience - the inner mechanics of the 416 Plus that would explain why this happens are beyond me. 

 

I had Media Blackout build me an RS to D-tap with 12v reduction cable, for small accessories. When I connected a monitor to this for power (we tested both the Convergent Design Odyssey7 through an AJA and TV Logic), and then attached the BNC, the Ground Fault light went on. 

 

We later tried going into the MM accessory port on the IVS to power the monitor - this time with a cable that was Lemo2(if that is indeed what the connector for MM is) straight to the monitor - and no Ground Fault occurred. 

 

This was all at a checkout bay at Arri New York, with several techs there working through my issue. We resolved that the Ground Fault is caused by RS-powered items connecting to the BNC on the IVS. It must have to do with the way the camera supplies power to the IVS, versus how the IVS provides power out of those MM outputs. 

 

I would love to test this on other modern-era Arri cameras like the Arricam or 2/4/535. Or even Moviecam. 


Edited by Kenny N Suleimanagich, 12 October 2015 - 03:19 PM.

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#15 davide sorasio

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Posted 12 October 2015 - 03:39 PM

all right! Thank you so much guys! You helped me a lot!


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#16 Satsuki Murashige

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Posted 12 October 2015 - 03:46 PM

I was thinking of ordering one of those custom regulated 12v R/S to d-tap boxes from Alan for my Moviecam. Never got around to it, will let you know how it turns out if I ever do it!
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#17 Satsuki Murashige

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Posted 12 October 2015 - 03:53 PM

Davide, I'm not an expert in electricity at all, so I'm not sure I can answer that question. Paging Phil Rhodes...
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#18 davide sorasio

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Posted 12 October 2015 - 03:58 PM

in case anybody knows, i was wondering about this: Ive noticed that most gold mount/V mount on camera batteries have a 14V voltage, so why is it possible to power a tv logic directly to the battery through a dtap when the tv logic requires 12V? shouldn't it create a short circuit?


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#19 Satsuki Murashige

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Posted 12 October 2015 - 04:47 PM

Try not to post the same question twice in different threads. From your other thread:

Satsuki Murashige
Today, 02:04 PM
No, it won't create a short. If the battery has too high of a voltage at full charge (a lot of these batteries can provide up to 18v), then you risk blowing a fuse in the 12v device or damaging the electronics if there is no fuse. TVLogics are usually fine on d-tap, but with a full battery it's best to power on the camera first and let it run a bit before plugging in accessories so they don't get the full current.

Now, if you plug the d-tap in backwards, reversing the polarity of the hot and neutral pins then you will cause a short and immediately fry your device. I know it seems impossible to do, but I think everyone who's been around long enough has done it once...
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