Artnet interface discovery by QLC+

All the topics related to QLC+ on the Raspberry Pi
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rowanpaul
Posts: 3
Joined: Mon Feb 12, 2018 1:10 pm
Real Name: Paul Rowan

Hi Guys, I've successfully loaded OLC+ onto a Pi model A and am talking to the Web interface fine at a fixed IP address on a powered hub uplinked to my home router (in a reserved IP address range). The Pi is at 192.168.1.202 and my normal SmartShow Artnet interface is at 192.168.1.201 on the same hub (avoid broadcast routing problems) I can use the Smart show and see it from both m-PC and my phone running Art-Net Controller by Litux connected to via the home router.
How would does QLC+ on the Pi discover Artnet interfaces please? In the config page of the web interface only the loopback 192.0.0.1 and 192.1368.1.202 are listed.
Any pointers would be appreciated many thanks
Paul
rowanpaul
Posts: 3
Joined: Mon Feb 12, 2018 1:10 pm
Real Name: Paul Rowan

Hi guys I'll answer if that's okay so anyone else trying to do this will have a pointer.
A number of ArtNet devices do not always auto-discover depending on several factors so we have to send blind as it where.
I'm using a SmartShow ArtNet DMX interface which is discovered by programs such as ArtNominator but not M-PC.
In the http://www.qlcplus.org/downloads/4.11.1 ... 4.11.1.pdf page 115 the use of unmapped interfaces is described.
Select Input or Output on your Artnet Plugin on say your local machine ethernet interface "192.168.1.103" then select the tools button where there is now a table with provision to enter your ArtNet interface and the transmission mode.
kbuehler
Posts: 1
Joined: Mon May 22, 2017 12:44 pm
Real Name: Klaus Buehler

Sorry for the late post. But I think, it is important to state, that this behaviour is definitely a bug, See screenshot below.
Screenshot from 2019-09-30 12-39-49.png
The ArtNet specification clearly defines for ArtDmx packets the following "packet strategy: unicast transmit: yes, Broadcast: no"!
For the for unicast subscription process it states:
If there are no subscribers to a universe that the transmitter wishes to send, then the ArtDmx must not broadcast. If the number of universe subscribers exceeds 40 for a given universe, the transmitting device may broadcast.


The packet dump clearly shows 2 things
  • QLC+ sends ArtPoll request and my Node responds timely
  • QLC+ does not behave as expected. It does not show the node as a result of successful discovery on input/output tab. It does neither start sending DMXChannel packets as unicast to 192.168.0.58. It just ignores the result of its poll request and uses broadcasts instead
I find this a well-known bug, since somebody asked much earlier for the possibility to enter the IP-address of a node manually just because of the inability of QLC+ to detect and show ArtNet nodes.
This possibility has been added, but in an inconsistent way, as I find. You do not add a node manually as I would expect, instead one must manually add the node's IP-address to the local output definition. Then and only then, QLC+ uses unicasts as required by spec.

Generally spoken, sending ArtDmx packets as broadcast not only violates the spec, it is also a rather bad idea. Some of my DMX fixtures do not respond at all, others erroneously, unreliable and extremely delayed. This definitely is of no use. It leads inexperienced users to the assumption, that their equipment is malfunctioning.
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