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Difference between revisions of "Logic RDM Sniffer"
From wiki.openlighting.org
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You need some hardware to convert from the differential 485 levels to a signal which the logic can understand. | You need some hardware to convert from the differential 485 levels to a signal which the logic can understand. | ||
| − | At the basic level you only need an RS-485 receiver like the Maxim MAX485 or Linear Technology LT1785 to translate from the DMX/RDM differential levels to a TTL level that the Saleae Logic | + | At the basic level you only need an RS-485 receiver like the Maxim MAX485 or Linear Technology LT1785 to translate from the DMX/RDM differential levels to a TTL level that the Saleae Logic understands. |
| − | [[File:RDMSnifferSchematic.jpg]] | + | [[File:RDMSnifferSchematic.jpg|thumb|center|400px|alt=Example Circuit]] |
== Software == | == Software == | ||
Revision as of 06:58, 16 September 2013
The Saleae Logic makes an excellent DMX / RDM sniffer. With the Logic and a small amount of hardware you can build a sniffer for a fraction of the price of commercial units.
Parts
- A Logic or Logic 16, but see the note below.
- 485 driver circuit
- XLR connectors.
Electrical
You need some hardware to convert from the differential 485 levels to a signal which the logic can understand.
At the basic level you only need an RS-485 receiver like the Maxim MAX485 or Linear Technology LT1785 to translate from the DMX/RDM differential levels to a TTL level that the Saleae Logic understands.
Software
Saleae Logic
Saleae provides the Logic App which works on Windows, Mac and Linux. The application has a plugin to decode DMX, but it doesn't understand RDM data. The tool is best for analyzing the signal timing rather than the high level messages.
OLA Sniffer
OLA has a text-based DMX/RDM sniffer that works with the Logic (it could easily be extended to work with the Logic 16). It can be found in tools/logic directory of the OLA sources.
Limitations:
- the sniffer doesn't understand DUB responses yet since it looks for breaks.
- it may struggle with signal timings that are at the edge of the E1.11 standard. If you experience problems with the sniffer please email the Open Lighting Mailing List
