FB3 and RJ45 (cat5)

[aijii]

what kind of bandwidths are we talking here for 30K ILDA with 4 colour channels ?

I thought of this about a year or two ago. Would be quite rad.

[Stoney3K]

I wouldn't be in favor of using IP (or even Ethernet) for such an application.

From an audience safety's POV, it is imperative that your projectors will receive the same data as was sent from your system. A scan-fail system can act on projectors receiving no ILDA input, or malfunctions in the projector, but it will not handle ILDA signals that were somehow garbled along the signal's path.

A projector will happily display erroneous ILDA data, for the simple reason that it has no method to verify that it was the actual data sent from the other end -- it has only analog inputs.

Furthermore, TCP/IP or Ethernet will not guarantee any timing. When you are doing a show which features multiple projectors and has some method of synchronizing the projectors with each other and/or other equipment, the synchronization may drift as the frame data is transmitted over the network and may arrive at different times for different projectors (because of switching delays). As the times and intervals are not fixed, you will need to buffer the frame data, introducing a larger delay for which you have to compensate when using real-time control. The problem is even worse when you go wireless.

Lastly, if the network segment is shared with other Ethernet devices, your traffic and/or timing may get fraggled up because of the traffic generated by the other computers or devices on the system.

Sure, using an Ethernet- or IP-based solution may be attractive because it allows you to use any computer as a laser show controller out of the box. But the drawbacks need to be considered, that's also the reason we don't like to send audio or video information on a network when using networks on stage.

As an alternative, if you want to use Category 5 unshielded twisted pair cables with RJ45 connectors (commonly known as network patch cables) for the simple reason that they pose less demands on infrastructure, are easier to carry and a lot cheaper, then it may be a good idea to just consider the CAT5 cable as an electrical connection, instead of immediately drawing the conclusion 'Ethernet', for an example pinout:

+1 : Data RX +
-1 : Data RX -
+2 : Clock +
-2 : Clock -
+3 : Data TX +
-3 : Data TX -
+4 : Interlock A
-4 : Interlock B

This takes full advantage of the twisted pair nature of a CAT5 cable by transmitting each digital signal in a balanced differential fashion. Synchronous data transmission is preferred because it fixes the timing of the system to a certain value.

There is a return channel where projectors or other devices can 'report back' any status information or malfunctions, and the Interlock loop can be doubled up on the digital circuit, so it will disengage on the other end if the digital transmission is somehow scrambled.

The data transmission/reception circuitry should be no more difficult than an ADC/DAC for each channel (XYRGBI), a set of shift registers for serialization and some control circuitry (like an AVR microcontroller) for flow control and device management.

*if* you want to go the Ethernet route, you can consider using a 'frame buffer' in each endpoint and only send trigger signals over IP, in the same way video media servers work. However, since you're still going to need a hard line from your front-of-house to connect your emergency stop system, I fail to see the added value from that. The hard line itself could just as simply be a CAT5 cable carrying all the data we want.

[sjmackinder]

I have used 3 FB3's on a 95m CAT5 cable with USB converters either end, the show was outdoors and the FB3's behaved perfectly all night. Up to 4 USB2 powered ports support 4 FB3 units over a max distance of 100m

[Stuka]

I have used 3 FB3's on a 95m CAT5 cable with USB converters either end, the show was outdoors and the FB3's behaved perfectly all night. Up to 4 USB2 powered ports support 4 FB3 units over a max distance of 100m

What brand / model converters were you using?

[Bbe]

Hey guys!
A long time ago I found a solution: on the projector side i use microcomputer with linux os and usb over network software (server side). On my laptop (client side) QuickShow + usb over network client. It works great!

[sjmackinder]

They are made by Startech

[Stuka]

Hey guys!
A long time ago I found a solution: on the projector side i use microcomputer with linux os and usb over network software (server side). On my laptop (client side) QuickShow + usb over network client. It works great!

I just started experimenting with that type of software myself, since I already have a micro PC dedicated to a Pangolin QM2000.
I've tried it with Q2, LivePRO USB, and Enttec DMX Pro USB interface, and so far it looks promising!

[sjmackinder]

Thing is, with the USB/CAT5/USB approach there is no software or additional PC's/computers it is simple and works as though you are sitting right next to the FB3's and ILDA cables - totally transparent. The converter modules are no bigger than a matchbox!

[djpsych]

Are you talking about the StarTech USB2001EXT2, USB2002EXT2, or USB2004EXT2? That costs about ~$350-460.

[White-Light]

Are you talking about the StarTech USB2001EXT2, USB2002EXT2, or USB2004EXT2? That costs about ~$350-460.

I had a look earlier because I was interested ib the concept and this looked like the most likely product due to the 4 inputs:

http://intrl.startech.com/Networking...orts~USB4000IP

$89 each but still not cheap when a pair are needed.

Only sjmachinder can confirm though.