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Old July 9th, 2008, 08:50 PM   #1
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RS-232c vs RS422 in Sony camera products

I have been tasked with hooking up 3 Sony BRC-300 cameras with 1 BRU-300 remote control. What are the pros and cons of using RS-232c connections vs RS-422? Any system integrators out there who can shed light.

The only significant difference I can find so far is that RS-422 can be run over a longer distance. This will be fairly short runs so that is not really an issue.

A second question; I know that I can daisy chain the cable to the cameras but can I run 2 branches? I have a control station that will be on the North wall, 2 cameras on the East wall and 1 on the West wall. It will be a huge hassle (due to infrastructure of the building) to run a line from the command station to the East wall, thru two cameras and then accross to the West wall. I would like to have the line leave the BRU split into 2 lines, one running West to that camera and then the other running East into first camera and then daisy chained to second camera. If doing this then obviously I would have to manually assign addresses to the cameras instead of allowing the system to address the cameras automatically.

If anyone has experience they would like to share I would be grateful.

Thanks

Randy
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Old July 9th, 2008, 10:11 PM   #2
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Hi Randall............

From my days implementing RS 422 networks (a lifetime ago!) the advantage of 422 as opposed to 232 was it's relative invulnerability to signal degradation with greater cable length.

It's (usually) two twisted pair cableing also made life a whole lot easier (than 232) when it came to cable makeup for "difficult" runs/ situations.

Provided you keep the data rate down, I can see no reason why you couldn't run the cable to the West wall from the Controller in 8 core (4 twisted pairs), thus acheiving a "daisy chain" back to the controller, which you pick up and feed through to the other two cameras on the East wall link (this is assuming that the Sony implementation of 422 does actually use 2 twisted pair).

I can't quite see what type of connectors the Sony cameras or controller use, but as long as it's something easilly obtainable should be a doddle to implement.

At each end of the East wall link cable you fit two connectors. One is the Out link, the other the Return link.

At the controller end, one (the out) is connected to the controller, the other (the In) goes to the West wall link. Obviously, at the East wall camera, both out and in are connected to their respective ports.

The 422 spec does actually allow up to 10 receiver ports to be connected to one transmitter port, the bugger is it doesn't allow for more than one transmitter. If the cameras simply listen and obey, everything's cool, if they "talk back" you have to daisy chain.

Hope this is of some use.


CS
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Old July 10th, 2008, 01:03 PM   #3
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Thanks for the reply

Here is a link to the manual. On page 28 of the PDF is the diagram showing hook up. It seems that there is a tx and rx side as well as a seperate ground. I had not really thought of it but I should be able to run this as Cat5 cable. There is no specification that says twisted pair is needed but it certainly can't hurt.

http://www.broadcaststore.com/pdf/mo...55/rmbr300.pdf

The 232 connector is a 8 pin mini din, I hate them, and the 422 is an inline 9 connecter plug. The more I think about it the more I like the 422. I think what I will do is run a Cat 5 cable from the east wall to the control station, then run it as well as a second cat5s from the control station to the west wall. Then my physical chain will run from the control station the west wall to camera 1 then to the east wall for camera 2 and 3.

Do you forsee any problems using cat 5 cable. I am most familiar with it. I think you and I are thinking along the same lines, but I just wanted to make sure I did not overlook anything. I am doing the hook up but they are having a crew come in and actually run the cables so I want to get it right the first time. ;)

Thanks for your input.

Randy

BTW: the control unit is the RM-BR300, the item I listed above is a fiber optic multiplexor....thankfully we won't be needing that.
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Old July 10th, 2008, 04:03 PM   #4
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Hi.............

The suitability of Cat 5 will depend pretty much on the cable run length. I wouldn't like to put myself out on a limb and give a definate YES only to find the run is too long for the cable type.

The problem is the capacitance between conductors. The sheathing on Cat 5 is incredibly thin, so the conductors tend to have quite high self capacitance, which gives the 422 drivers more work to do. Too long a run and they just can't switch the levels fast enough. That said, you could probably run a moderate network using coat hangers if needed.

If it was my ass on the line I'd try a test run with a roll of Cat 5 to check it out first, cable installers ain't cheap.

I agree wholeheartedly about Mini Din connectors, I can barely see the connectors let alone work with them.

Can't say as I've seen that type of 9 pin in - line connector before tho', are they easilly getable?

Overall, sounds like you're on the right track.

Let us know how it goes.

Oh, I'm intrigued BTW. East wall, West wall, North wall. Almost sounds like the exercise yard at the local penn?


CS
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Old July 11th, 2008, 10:34 AM   #5
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Originally Posted by Chris Soucy View Post
The suitability of Cat 5 will depend pretty much on the cable run length. I wouldn't like to put myself out on a limb and give a definate YES only to find the run is too long for the cable type.

The problem is the capacitance between conductors. The sheathing on Cat 5 is incredibly thin, so the conductors tend to have quite high self capacitance, which gives the 422 drivers more work to do. Too long a run and they just can't switch the levels fast enough. That said, you could probably run a moderate network using coat hangers if needed.
I've always wanted to try that, just for the fun of it. I don't really think that the run will be too long, certainly under the 1200 METERS that it says 422 will handle. Finally found a spec for the wire....AWG 28 to 18. I'm off now to take a closer look at the box of Cat5 I have.

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If it was my ass on the line I'd try a test run with a roll of Cat 5 to check it out first, cable installers ain't cheap.
These are fairly cheap.....county prison crew. See below for expanation.

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Can't say as I've seen that type of 9 pin in - line connector before tho', are they easilly getable?
I've seen them with several broadcast pieces now with a variety of pins from 4-18. Seems like a fairly standard connector that I have seen in electronics, automotive, and even an appliance or two. Radio Shack has some similar stuff though this connector looks like it has some hooks for making sure the plug does not come out inadvertantly.

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Originally Posted by Chris Soucy View Post
Overall, sounds like you're on the right track.
Thats what I was hoping to hear, thanks.

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Originally Posted by Chris Soucy View Post
Oh, I'm intrigued BTW. East wall, West wall, North wall. Almost sounds like the exercise yard at the local penn?
Nope. Sounded easier to explain than wall 1 2 and 3. Most everyone would understand that the East wall is directly accross from the west wall. This is actually a county commission chambers. I'll have 2 cameras facing the commissioners, 1 facing the opposite way for public speakers at the podium, and the control room is on one of the side walls.

Thanks again for your input. I'll let you know how it goes once I get started. The county electrician who is going to work the inmate crew to run the cables and set power has been sick and in the hospital so I don't know when I will be able to get started. While its not moving fast I am trying to study as much of it as possible, while we have access to the inmate crew for free labor, I don't want to make them have to redo anything because I was not prepared.

Randy
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Old July 11th, 2008, 04:24 PM   #6
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Hi again.........

I'm interested in what sort of video you'll be piping out of these things?

I noticed in the blurb on the BRC 300 it can O/P Composite & S video out of the box, and Component (I presume YPbPr), RGB and even HD SDI with the appropriate slot in cards.

I presume you're planning on using a video switcher to select your feed?

What's the ultimate destination?

Finally, I know you probably know this, but just in case it's been overlooked, the camera's use a mains - 12 V power adapter, so guess you'll need an adjacent mains socket for each one.

A "gotcha" with this is that if, in a commercial premises, the sockets are on different phases of a 3 phase system, issues CAN arise between the various cameras and the switcher and equipment further (up or down) the food chain.

It's so design dependant I can't predict you will have any issues, but if you're getting in a crew gratis, ensureing "all same phase" wouldn't go amiss.


Good luck.


CS
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Old July 11th, 2008, 05:41 PM   #7
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Oh...........

Just to save you asking the inevitable question about that last point in my previous post, the issues and causes are thus:

In the old linear (transformer, rectifier, series pass transistor, smoothing capacitors etc) "wall warts" or internal power supplies, inadequate filtering or feedback interference to the transistor/ control chip allowed a 50/ 60 cycle "hum" through to get into the gubbins down the line.

This could cause interesting strobeing effects from (some) cameras, but vision mixers especially as "hum" met mixer electronics.

The newer switch mode wall warts/ internal power supplies have introduced a whole new level of problems caused by inductive pickup internally and inadequate or zero grounding (using appropriately sized resistors) of the O/P lines.

This means that some of these new power supplies can have both the (theoretically) Ground and +12 or whatever floating at anything up to 110 Volts AC (Sadly, I jest not!).

The O/P impedence of this AC is very high, but in the right circumstance can still give you a good belt, as I can attest. This is despite said wall warts and power supplies being fitted with earth pins on the mains side (go figure!).

I doesn't take too much imagination to figure out what 3 phase (or even 1 phase, come to think of it) 110 Volt AC can do if let loose in a network of any sort of equipment.

To make matters worse, most A/V equipment nowadays is not earthed, so once this stuff is in the system it can cause some interesting side effects till it does, eventually find an earth point.

To test one of these power supplies, you need a good, high input impedance (30K ohms / volt or higher) multimeter set to the AC 125 or 250 Volt range (NOT Amps!!). Test each of the power O/P connections, with the other probe stuffed into the earth connector of a mains socket (do get the right hole & meter setting here - a screw up could be nasty).

The higher the I/P impedence of the meter the higher the voltage you will see.


CS

Last edited by Chris Soucy; July 12th, 2008 at 01:53 AM. Reason: Wheb wilk I learm to proog tead thus stiff?
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Old July 14th, 2008, 01:29 PM   #8
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A "gotcha" with this is that if, in a commercial premises, the sockets are on different phases of a 3 phase system, issues CAN arise between the various cameras and the switcher and equipment further (up or down) the food chain.

Amen brother, preach on.....can I get a hallelujah from some one!!!!!! Been there done that. Church I was attending fried a projector that way and had a sound system that would bite you each time you tried to move a cable. I finally started running power and data from the balcony to the projectors to try and protect them.

The ultimate destination is local cable via the PEG channel. May eventually make it to county's web site too. I work for the local library where we have one side of the head end for the PEG. We have 5.5 hours primetime weeknights and a local community college has the remainder of the time.

This will actually be a duplicate of the system the city installed a little over a year ago. Footage from it can be seen by clicking 'Video on Demand' at this page:

http://www.romega.us/index.asp?nid=146

Also you can see me operating the system in one of my DVC entries by clicking here:

www.mailxp.net/dvc9/dvc.htm

Thanks again for your input.
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