Lor E1.31 Observation - Data Always Sent When Comm Listener Is Running

[heystew]

Mostly an observation, not a complaint, because I haven't yet figured out whether I like it or not.

Using wireshark I noticed that while the Comm Listener is loaded it will always send out E1.31 packets regardless of whether you are playing a sequence or not. The packets appear to be full size packets just no intensity data.

This has several impacts.. some good.. some i'm not sure about yet..

1. Good - the cheap 3 channel DMX controllers will stay dark because data is being provided at all times (if using an E1.31 to DMX bridge)

2. Bad - because there is still data available to an E1.31 controller (E681 for example), it overrides the controllers No Data Timeout function. I have mine set to turn off the lights 5 seconds after it stops receiving data.

3. indifferent - lots of data on the network at all times, so probably another reason to keep this on a separate network

dave

{--- Now that I think about it.. this post most likely belongs in the S3 Software section, not the Hardware/DMX section ---}

Edited July 14, 2012 by heystew

[Tim Fischer]

For what it's worth, the iDMX always sends DMX data constantely, even if it's not even connected to an LOR network. I definitely liked that with the cheap 3-channel controllers.

[Don]

{--- Now that I think about it.. this post most likely belongs in the S3 Software section, not the Hardware/DMX section ---}

Moved by request.

[jeffl]

How much is? Lots of data on the network at all times? I'm wired for 100 mbit/s and was hopoing that would be way overkill.

[heystew]

You are right, "lots" is relative and most likely usually never an issue. I'm not actually that worried about it just wanted to point it out.

As for how much data it really is...

With the packets coming out 50/sec and each is 680bytes, it works out to 272kbits/sec for each universe. At 20 universes, it's just over 5 Mbits/s.

Not a problem for most networks, although since it is multicast it very well may be sent across a connected wireless network which may not have the same capacity as a wired network.

[jeffl]

This is all good information to know. I'm sure we will all get a little extra network education this year. I think for the Lynx Express units I have the constant packets are a good thing. Hard to say at this time.

[spomalley]

Interesting...although I think at the moment it has more pros than cons.

[-klb-]

Far more benifits. And there are work arounds, like running your E1.31 on a diffent network adapter, or using a router to separate the broadcast domains. Or using Unicast E1.31 devices.

[LOR Staff]

I'm no DMX expert, but I think that's how the specification is written. Even if there is no 'activity' for a DMX network, the packets are supposed to be constantly generated and sent. That's why intelligent DMX adapters are preferred to dumb ones - all that packet generation is passed off to the adapter.

In our world, E1.31 is nothing more than DMX over Ethernet. Since the DMX spec requires those packets to be generated, we have to generate them and pass them off to the network. That's the traffic you see.

Think of the 'No Data Timeout' as a fail-safe. Should something happen to the data transmission path, those devices will shut themselves off (instead of burning out).

[crackchecker]

_{So what is the physical connection with E1.31? From computer on USB to (ENTTEC PRO) to module to lights still???}

_{Please enlighten....}

[heystew]

E1.31 uses ethernet. Using the network card on your computer. No USB dongle required.

Connection is:

Show pc > ethernet > e1.31 contoller > rgb pixels

An example of the controller is a sandevices E681 or a j1sys pixel controller. Also stellascapes and others

[spomalley]

_{So what is the physical connection with E1.31? From computer on USB to (ENTTEC PRO) to module to lights still???}

_{Please enlighten....}

Unlike what your used to, E1.31 comes through your computer's LAN port with no dongle to an E1.31 device then to pixels. Its a new way of connecting with controllers, the reason for this change is because the large number of channels (as a result of the RGB revolution) needs a higher speed connection that can handle larger data, the solution to this came from the development of E1.31 which allows tens of thousands of channels to come through that one port in your computer.

EDIT: Beat me to it Heystew.

Edited July 16, 2012 by spomalley

[LOR Staff]

FYI.....

While many are using E1.31 with pixels, please note that E1.31 is NOT exclusively for pixels.