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kfindley
08-09-2009, 11:12 PM
I can not get my DMX to work for anything. i have the the DMX by rpm. vixen is setup corectly for it. its built correctly. When i go to program it both lights come on continuously. but wen i go to run a program the red led just keeps blinking. and nothing happens

please help

DynamoBen
08-10-2009, 12:22 AM
Its hard to help because your description has only symptoms, we need more information to troubleshoot.

What have you done? How are things hooked up? What are equipment are you using? What are the start addresses set to? What version of Vixen are you running?

Matt_Edwards
08-10-2009, 01:07 AM
i know a lot here like to use the on board terminator, but i would reccomend you biuld a DMX LED Terminator
they are dead simple and a good sample can be found here http://www.bigclive.com/dmxtest.htm

You soon learn differences in the colours let you if a cable is stuffed.

As DB said help us help you. What have you tried, what do you heave available to test and how do you know if one or more components are working.

I try to work on the old adage "change one variable at a time" so sort out these types problems.

Cheers
Matt

intwoit2002
08-10-2009, 01:51 AM
This sounds very familiar. Are you using a Renard PIC programmed for DMX? If yes then I am having the same problem. One thing Robert told me was that it has to be used on USB 2.

He has been extremely supportive to me.

I have finally bought a light that is DMX capable to use as a reference.

Al

kfindley
08-10-2009, 03:57 AM
Its hard to help because your description has only symptoms, we need more information to troubleshoot.

What have you done? How are things hooked up? What are equipment are you using? What are the start addresses set to? What version of Vixen are you running?

I am in the understanding that it gets hooked up through the cat5 on the back of my pc (Pentium 4 2.14 gh. built from extra parts vixen 2.1) witch i have done. I have followed the directions that was on the ass. man. that came from rpm on how to program it. Cant remember my start addresses.i am using it for the grinch witch i know work flawlessly with out the dmx hooked up.

kfindley
08-10-2009, 03:59 AM
This sounds very familiar. Are you using a Renard PIC programmed for DMX? If yes then I am having the same problem. One thing Robert told me was that it has to be used on USB 2.

He has been extremely supportive to me.

I have finally bought a light that is DMX capable to use as a reference.

Al

not sure cuz its the one that RPM had with the kits and they where preprogramed

dmcole
08-10-2009, 11:48 AM
I am in the understanding that it gets hooked up through the cat5 on the back of my pc ...

Uh, no: It's hooked up through your USB port. As intwoit2002 said, it should be a USB 2.0 port.

\dmc

RPM
08-10-2009, 12:25 PM
Uh, no: It's hooked up through your USB port. As intwoit2002 said, it should be a USB 2.0 port.

\dmc

Yes, it's hooked up to your computer through a USB2.0 port.

Basically, it's PC-->DONGLE-->GRINCH DIMMER-->GRINCH

The only Cat 5 cables are from the Dongle to the Grinch Dimmer, then from the Grinch Dimmer to the Grinch.

I'll attach a simplified diagram.

kfindley
08-10-2009, 01:27 PM
thats why i called this one im a retard. i got this now someone wat. now wat dongle do u recommand for this

DynamoBen
08-11-2009, 08:03 PM
thats why i called this one im a retard.

BTW I changed the thread title to something more descriptive, which should attract more help.

kfindley
08-16-2009, 04:03 AM
so im assuming i am able to use this here http://www.enttec.com/index.php?main_menu=Products&pn=70303&show=description&name=opendmxusb. and if so how do i hook up the cat5 to i t

Matt_Edwards
08-16-2009, 05:18 AM
so im assuming i am able to use this here http://www.enttec.com/index.php?main_menu=Products&pn=70303&show=description&name=opendmxusb. and if so how do i hook up the cat5 to i t
yeah they work OK.

check out the wiki for a connection table between the 5pin cannon to RJ 45
http://www.doityourselfchristmas.com/wiki/index.php?title=DMX

RPM
08-16-2009, 06:58 PM
so im assuming i am able to use this here http://www.enttec.com/index.php?main_menu=Products&pn=70303&show=description&name=opendmxusb. and if so how do i hook up the cat5 to i t

The Enttec USB Open will work, but it does have timing problems and a better choice would be the Enttec USB DMX Pro
(http://www.enttec.com/index.php?main_menu=Products&pn=70304&show=description&name=dmxusbpro) You will need to build a 5 pin XLR to Cat5 adapter for either of the Enttec dongles.

I also have a DMX dongle design that can recommend. You can read about it here http://doityourselfchristmas.com/forums/showthread.php?t=7009
I will be doing a co-op of this design very soon.

Robert

DynamoBen
08-16-2009, 08:30 PM
The Enttec USB Open will work, but it does have timing problems...

And what problems are those?
I've used my homemade one for a few years now and it works great. Further when KC and I were developing the plugin for it I used a professional DMX tester (Goddard Design lil'DMXter) to verify timing and multiple other parameters.

The Pro is a good choice if you intend on using the advanced features, have a crappy computer running your show (very high CPU usage), or if you have some extra money lying about.

kfindley
08-16-2009, 09:10 PM
ill seen something on ebay witch im beleive i may buy and and also looking forward to being a part of the Co-op. I rather be safe than sorry so if i get wat u desighned and one of them i always have something to fall back on. plus i love building things. it make it more fun and i feel more proud of my display

RPM
08-16-2009, 09:22 PM
The DMX Open output is not buffered, so it requires a constant stream of data from the computer and anything that interrupts this process will cause data loss.
It's most apparent when running at 25ms, but can happen at slower frame rates as well.
The USB Pro (and my dongle design) buffers all data from the computer, so this isn't an issue.

I have a few Vixen routines at 50ms that run poorly on the DMX Open that have poor fade in and fade outs that do not fade smoothly and occasionally miss channels, but with the Pro (or my Pro compatible design) dongle they are very smooth. This is with an P4 3.4Ghz 2Mb cache CPU with 4Gb ram in the machine, so it's not a computer limitation.

I'm not saying the Open isn't usable, it's just not the same performance as you would get from a USB DMX Pro and it costs about the same to buy an Open or build a Pro compatible dongle.

Robert

DynamoBen
08-16-2009, 09:41 PM
The DMX Open output is not buffered, so it requires a constant stream of data from the computer and anything that interrupts this process will cause data loss.
It's most apparent when running at 25ms, but can happen at slower frame rates as well.
The USB Pro (and my dongle design) buffers all data from the computer, so this isn't an issue.

I have a few Vixen routines at 50ms that run poorly on the DMX Open that have poor fade in and fade outs that do not fade smoothly and occasionally miss channels, but with the Pro (or my Pro compatible design) dongle they are very smooth.

Okay what you are seeing has nothing to do with a lack of buffering nor is it a timing problem, per say. What you are observing is a difference in refresh rates between the two dongles. The OpenDMX was intentionally lowered (based on the testing I performed) to ~33Hz to keep things stable on longer USB connections and slower computers. At 33Hz the fastest you can update data is every 30ms. Whereas the pro has a refresh rate of ~44Hz which can be updated every 22ms.

Honestly in practice, with the OpenDMX, I wouldn't go below 50ms but would suggest a sequence start at 100ms if at all possible.

BTW If you suspect that something is "interrupting the process" or causing inconsistent behavior then I need to talk to KC about the plugin because there might be a treading issue with it.

RPM
08-16-2009, 10:06 PM
Okay what you are seeing has nothing to do with a lack of buffering nor is it a timing problem, per say. What you are observing is a difference in refresh rates between the two dongles. The OpenDMX was intentionally lowered (based on the testing I performed) to ~33Hz to keep things stable on longer USB connections and slower computers. At 33Hz the fastest you can update data is every 30ms. Whereas the pro has a refresh rate of ~44Hz which can be updated every 22ms.

Honestly in practice, with the OpenDMX, I wouldn't go below 50ms but would suggest a sequence start at 100ms if at all possible.

BTW If you suspect that something is "interrupting the process" or causing inconsistent behavior then I need to talk to KC about the plugin because there might be a treading issue with it.

I'm not sure what was causing my problems but I'll admit that the Open DMX is a great low cost solution.

It wasn't my intention to start a "why brand A is better than brand B" discussion, my point is simply that a DMX Pro compatible can be had for a reasonable cost and work under a wide variety of setups which in my opinion makes it generally a better solution than the DMX Open is.

Robert

DynamoBen
08-16-2009, 10:31 PM
...my point is simply that a DMX Pro compatible can be had for a reasonable cost and work under a wide variety of setups which in my opinion makes it generally a better solution than the DMX Open is.


Fair enough the reason I responded was to separate fact from opinion. I respect the fact that you prefer the Pro (I'm sure I would too if I owned one), further I don't discount what you've observed with the Open. However I want people to have factual info/data about the Open. Once they have the facts they can consider people opinions and then make their choice based on their budget, features, and others preferences.

History Lesson: The primary reason the Open was the first, and only for a while, DMX dongle was because it works well and is inexpensive. Further its open source and could be built at home, unlike the Pro.

In the end we agree its down to features and function. If you need/want 44Hz refresh or intend on using the advanced features the Pro has then go for it. If however you want to save money and are whiling to "deal with" the slightly slower refresh the Open is a good choice.

Matt_Edwards
08-16-2009, 11:34 PM
Can I add one other issue to the open?
I own an original Enttec Open DMX not a home made one. I have had to replace the 485 driver chip way too many times ( More than 5 times).

I blame the fact that I live in the Hills, power surges are plentiful, and there is about 30m unshielded cat 5 between the dongle and the dimmers. The show computer and the dimmers are also on separate main phases. ( I have 3 phase power into the home)

I suspect the Pro will not help me here. Nor will RPM's open source unit as the isolation is in the wrong place. I need Isolation at the load end not the source end.

Am I on the right track?

Cheers
Matt

DynamoBen
08-16-2009, 11:54 PM
I own an original Enttec Open DMX not a home made one. I have had to replace the 485 driver chip way too many times ( More than 5 times).

I suspect the Pro will not help me here. Nor will RPM's open source unit as the isolation is in the wrong place. I need Isolation at the load end not the source end.

Am I on the right track?


Switching dongles won't help.

I've seen this happen when a building or site is struck by lightning. Typically I suggested they unplug the data line when not in use or put an opto splitter in line. Its cheaper and easier to damage and repair a splitter than a lighting console.

In your case I would start by "lifting" (disconnect) the shield on the DMX cable (Pin 1) at the dongle, on the cable side not dongle side. If the problem goes away the problem could be that the shield is tied to ground somewhere and that's where the spike is coming from. The source could be the USB side via your PC or it could be on the dimmer side. If its the PC side a UPS may correct this issue. If its the dimmer side the rule of thumb is the DMX transmitting device should have its shield tied to AC ground but the dimmers should have it lifted, so lift the dimmers.

RPM
08-16-2009, 11:57 PM
Fair enough the reason I responded was to separate fact from opinion. I respect the fact that you prefer the Pro (I'm sure I would too if I owned one), further I don't discount what you've observed with the Open. However I want people to have factual info/data about the Open. Once they have the facts they can consider people opinions and then make their choice based on their budget, features, and others preferences.

History Lesson: The primary reason the Open was the first, and only for a while, DMX dongle was because it works well and is inexpensive. Further its open source and could be built at home, unlike the Pro.

In the end we agree its down to features and function. If you need/want 44Hz refresh or intend on using the advanced features the Pro has then go for it. If however you want to save money and are whiling to "deal with" the slightly slower refresh the Open is a good choice.

Ben,

Maybe we need to have some sort of comparison of dongles in the Wiki?
This sort of discussion always seems to come up and I'm sure it would help to have more info on DMX dongles for one to make an informed choice.

I for one am always on the lookout for an inexpensive DMX dongle and have come across these two different designs on Ebay that seem to work well. They are basically the equivalent of a DMX Open dongle. I bought one of each and tested them with Vixen and they seem to work well enough.

http://cgi.ebay.com/USB-to-RS485-FTDI-interface-Board-75176-tranceiver_W0QQitemZ120451734113
At $18.45 shipped this one was cheaper, but the problem I had with this is shipping time; it took about 7 weeks to arrive.

and

http://cgi.ebay.com/PC-USB-to-RS232-RS485-UART-TTL-Signal-Converter-New_W0QQitemZ250482853953
This one got here within 3 weeks, but was a little more than the first. At $22.98 shipped it's still a deal.

The problem that both of these had was a lack of drivers on CD, but these are easily downloaded from the FTDI website.
The first unit had no instructions at all, but the second one at least mentions the FTDI website for the drivers.

As always, your mileage will vary...

Robert

DynamoBen
08-17-2009, 12:26 AM
Hmmm, I may consider adding that.

RPM
08-17-2009, 01:04 AM
Can I add one other issue to the open?
I own an original Enttec Open DMX not a home made one. I have had to replace the 485 driver chip way too many times ( More than 5 times).

I blame the fact that I live in the Hills, power surges are plentiful, and there is about 30m unshielded cat 5 between the dongle and the dimmers. The show computer and the dimmers are also on separate main phases. ( I have 3 phase power into the home)

I suspect the Pro will not help me here. Nor will RPM's open source unit as the isolation is in the wrong place. I need Isolation at the load end not the source end.

Am I on the right track?

Cheers
Matt

Matt,

Have you been having any problems with the RS485 chips on the receivers?

If not, then it could be the problem is related to some sort of common mode potential; IE, the voltage difference from the + & - data lines to the Ground line.
Generally, the only end that should be grounded is the signal source end and too high of a voltage between ground and either data + or - can cause the RS485 IC to burn out, as would a large difference between the data + and - lines, but since the + & - are running in a twisted pair it's less likely to be the cause due to common mode rejection.

The isolation that the DMX Pro provides is to prevent damage to your computer (and anything attached to it) to the data lines out in the field (galvanic isolation), but if you're having problems with high voltage spikes in the field even the DMX Pro will not likely prevent this problem.

Robert