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Hi, I have a big big problem, then I operate my mini DMX rig. it freezes up, #1 then I have my smoke machine near the the dmx cable "buit I moved ,y smoke machine", or then I switch on a fan, like a normal household fan type, what can be the problem, because it's not cool , and the only way to fix it is to unplug my dmx interface from the pc and plug it back in and restarts freestyler, and sometimes, I have to power down my dmx laser and power it back on because, the laser is the first thing that goes.....

Sounds like bad earthing, causing interference over the DMX line.

Onge wrote:Sounds like bad earthing, causing interference over the DMX line.

earthing there u say? on what part? because I really want to fix it

yofo wrote:

Onge wrote:Sounds like bad earthing, causing interference over the DMX line.

earthing there u say? on what part? because I really want to fix it

Your electrics, how can I say what part it's your rig, your power supply etc.

Onge wrote:

yofo wrote:

Onge wrote:Sounds like bad earthing, causing interference over the DMX line.

earthing there u say? on what part? because I really want to fix it

Your electrics, how can I say what part it's your rig, your power supply etc.

Well, I have a oksidizer USB DMX512, "homemade" do you know something about it?

yofo wrote:

Onge wrote:

yofo wrote: earthing there u say? on what part? because I really want to fix it

Your electrics, how can I say what part it's your rig, your power supply etc.

Well, I have a oksidizer USB DMX512, "homemade" do you know something about it?

No I don't know anything about this interface, but if you are turning things on and it is freezing then that sounds like an electrical problem to me. It might be there is something wrong with interface in that it is suseptible to interferance from other electrical equipment.

I personally would not use a home made DMX interface. I did build my firt one the Vellerman, it worked fine albeit the problems that remco_k has pointed out in various posts, also I think it was version 1 of FreeStyler that I used with it, but thought if I want to do this properly then I need a proper professional interface.

Ok, that makes sense, I need to save some money then for the new interface
but do you think it might be a ground problem, because I've opened the DMX device, and noticed that the shield pin on the xlr that goes into my DMX device, it's not connected to anything, only pin 1,2,3 is connected to the circuit board, can this maybe be the problem

yofo wrote: I have to power down my dmx laser and power it back on because, the laser is the first thing that goes.....

could it be the laser which causes the problem? I think it sounds weird it have to be restarted

yofo wrote:Ok, that makes sense, I need to save some money then for the new interface
but do you think it might be a ground problem, because I've opened the DMX device, and noticed that the shield pin on the xlr that goes into my DMX device, it's not connected to anything, only pin 1,2,3 is connected to the circuit board, can this maybe be the problem

Only pins 1, 2 & 3 are used. On cables the screen(sheild) should be conected to pin 1. Take a look at DMX cables on the DMX Wiki for a full explanation.

As far as I am aware the casings of XLR connectors for normal DMX use should not be connected to anything, if that is what you are refering to as the shield pin on the XLR, but looking at the pictures on the Elektor website it looks as if the casing is connected to the screen of the cable, I would then assume it is connected at the USB end as well. I can see red, green, black and white cables coming from the cable to the PCB, but cannot see from PCB to the XLR connector, I do not have an account with Elektor so cannot get the schematics.

The device is not opto-isolated, which means no electrical protection from whatever is connected to the DMX end, connect as 48V phantom line and see what happens, don't do this really.
This is one of the reason that the DMX512-A specification is based on using 5pin XLR connectors not the 3pin as a lot of us use because a lot of the equipment we use on use 3pin.

iv recently been playing with microprocessors and found the majority of freezes can be fixed by using decoupling capacitors between the datalines and gnd and also usinging some larger caps between the supply lines and gnd. Read my post abouti fixing the enttec open lockup fix

I use 3 Pin XLR for DMX 512 system, an online buddy of me, have built me the DMX adapter, because it uses a PIC, and I don't have any PIC programming hardware
I have just opened it and connected the Ground (Screen) to pin1 "ground" If I'm correct here, and I've also connected that same wire to the USB Ground (Screen) just to make sure, and I'm testing it out now, like we "speak"

yofo wrote:I use 3 Pin XLR for DMX 512 system, an online buddy of me, have built me the DMX adapter, because it uses a PIC, and I don't have any PIC programming hardware
I have just opened it and connected the Ground (Screen) to pin1 "ground" If I'm correct here, and I've also connected that same wire to the USB Ground (Screen) just to make sure, and I'm testing it out now, like we "speak"

That will not be right !!!!!!

I am getting out of this conversation as something nasty is going to happen and I am not going to get the blame. If you don't know about something and cannot get a fully qualified answer then leave well alone.

isn't ground = negative?
because if I take my multimeter and check my voltage on my USB 5v I get a 5v with the probes on positive and on the shield form the USB

No
ground is ground, sometimes it as also called common or earth.
negative is negative.

They are different things.

Take a look at the wiki for USB http://en.wikipedia.org/wiki/Universal_Serial_Bus just over half way down the page you will see the pin-outs and voltages.

Onge wrote:No
ground is ground, sometimes it as also called common or earth.
negative is negative.

They are different things.

Take a look at the wiki for USB http://en.wikipedia.org/wiki/Universal_Serial_Bus just over half way down the page you will see the pin-outs and voltages.

Ohk, I will quickly take that wire of my USB shield then, but then I tested it, the laser worked 100% without going out on me like always.
Whats the use of a shield then?

EDIT: and on DC circuits, ground is always negative and so for shield, everything is grounded, just a shield is grounded

after connecting the pin1 to shield on DMX plug from adapter, it doesn't fix my problem, and after connecting the shield from my USB to my shield on DMX, it works better, I've been messing with my fan, to make "noise" in the mains, and it refuses to freeze, do we have any experts here who can confirm, if my way is good or bad???

Be VERY careful NOT to confuse what is sometimes called ground / sheild / Earth / Brade from a 3 wire config. with common or negative on a DC voltage line (2 wire)

To clarify - a 3 wire system such as DMX or a balanced audio cable uses +,- & ground. Imagine a sine wave with a line running through the middle.
Anything above the line is posative +. Anything below the line is negative -. And the middle line is ground. In this example 'ground' or whatever its being called is a reference point for the + & -. On a DC voltage line there is a measurable difference between + & - and there is no reference point as such . This can be confusing when folk refer to the refence point as 'common' because this term is used in DC too.
So be careful not to confuse these two or thing can and will go bang.

Yofo - Adding a desk fan or other small inductive load to a mains curcuit could cause a problem but its not very likely. Adding a hard working fridge, freezer or AC unit is more likely.
DMX is sometime known as ' Dirty 485' and it is by nature a fairly rubbish (by todays standards) protocal which is highly prone to picking up 'noise'.
Now having said that for the most part you will be unlikely to have much trouble with DMX but you need to have a good reliable usb to DMX device.
From what I have read on this and other posts you have made, you dont and I think this is probably where most if not all of your problems lay.
My advice is to save up you pennies and buy an Enttec device after all this is the bit that talks to your fixtures and ultimatly is resonsible for whether you can put on a light show or not!

dmxlighting wrote:Be VERY careful NOT to confuse what is sometimes called ground / sheild / Earth / Brade from a 3 wire config. with common or negative on a DC voltage line (2 wire)

To clarify - a 3 wire system such as DMX or a balanced audio cable uses +,- & ground. Imagine a sine wave with a line running through the middle.
Anything above the line is posative +. Anything below the line is negative -. And the middle line is ground. In this example 'ground' or whatever its being called is a reference point for the + & -. On a DC voltage line there is a measurable difference between + & - and there is no reference point as such . This can be confusing when folk refer to the refence point as 'common' because this term is used in DC too.

So be careful not to confuse these two or thing can and will go bang.

yea I understand this part, on a balanced cable, it have a + and - and ground, and then shield, do you think its safe to connect a shield onto a ground on the dmx cable?

On the circuit diagram from my DMX adapter, the ground from the DMX line goes directly to the USB negative pin via the circuit, but there is nothing shown the shield is connect to, it's unused


my addon:
and then on the USB side, I connect the shield of the USB to the USB negative pin
and then >>
connected the pin1 from the DMX to the DMX shield, and then hooked up the both shields with a wire inside my DMX adapter, and now, my laser doesn't freeze anymore then for example, then I turn on a induction device which makes a spike, like a fan. It used to just crash my DMX device

dmxlighting wrote:Be VERY careful NOT to confuse what is sometimes called ground / sheild / Earth / Brade from a 3 wire config. with common or negative on a DC voltage line (2 wire)

To clarify - a 3 wire system such as DMX or a balanced audio cable uses +,- & ground. Imagine a sine wave with a line running through the middle.
Anything above the line is posative +. Anything below the line is negative -. And the middle line is ground. In this example 'ground' or whatever its being called is a reference point for the + & -. On a DC voltage line there is a measurable difference between + & - and there is no reference point as such . This can be confusing when folk refer to the refence point as 'common' because this term is used in DC too.
So be careful not to confuse these two or thing can and will go bang.

Yofo - Adding a desk fan or other small inductive load to a mains curcuit could cause a problem but its not very likely. Adding a hard working fridge, freezer or AC unit is more likely.
DMX is sometime known as ' Dirty 485' and it is by nature a fairly rubbish (by todays standards) protocal which is highly prone to picking up 'noise'.
Now having said that for the most part you will be unlikely to have much trouble with DMX but you need to have a good reliable usb to DMX device.
From what I have read on this and other posts you have made, you dont and I think this is probably where most if not all of your problems lay.
My advice is to save up you pennies and buy an Enttec device after all this is the bit that talks to your fixtures and ultimatly is resonsible for whether you can put on a light show or not!

The fan I'm talking about is a 18" metal blade fan, it's like industrial type fan

OK, my trick worked, it made sense to me, that the shield absorbs some noise/spikes, and it needs a way to get ride of the noise/spikes that crashes my DMX rig, so it needed to be grounded to some source

3 Pin XLR

1 Signal Common Earth / Ground / Shield
2 Data Minus Negative signal
3 Data Plus Positive signal

http://www.leadsdirect.co.uk/technical/dmxwiring.html

yofo wrote:1 Signal Common Earth / Ground / Shield

Meaning: the common ground of that signal. Not the common ground of the entire installation and everyting hooked up to it.

Common Earth / Ground / Shield, the same thing, so I hook up the shield onto the Ground, and then hooked up that stuff onto my USB shield that is internally hooked up onto my USB Negative, Ground, whatever, and now, that part is more stable, I only have one problem on my rig, and my adapter freezes up then I physical power down my laser and power it back on while it's busy in FS, might be because my adapter doesn't have a opto-isolator in it, or the laser is a cheap brand name like JB systems, only the laser, the other stuff doesn't do anything, my cheavet dmx smoke machine doesn't freeze up the system, if I physical power it on and off and messed around with it. it just doesn't care, so it's either FS or my laser that crashes the system, it has always happened from the start, but I was never able to pin point the problem, because there was to many random problems with it, but luckily start's sorted out now, now I only have to fix this one problem, then my rig will work 100%

remco_k wrote:

yofo wrote:1 Signal Common Earth / Ground / Shield

Meaning: the common ground of that signal. Not the common ground of the entire installation and everyting hooked up to it.

As remco_k has said and I mentioned in an earlier post they are not they same thing.

Onge wrote:

remco_k wrote:

yofo wrote:1 Signal Common Earth / Ground / Shield

Meaning: the common ground of that signal. Not the common ground of the entire installation and everyting hooked up to it.

As remco_k has said and I mentioned in an earlier post they are not they same thing.

I appreciate you knowledge and responds, but your 2 are not the only people that know about DMX, I have talked to other people also. and they don't think my idea will do any harm to the system, and after doing that tweak a couple of weeks ago on my dmx adapter, it's every much more stable now, it doesn't just go of any more for random reasons like if you turn on a fan, I just have this one problem left with my laser freezing up the dmx adapter and no one seems to know, the only tip I have got is to get a opto-isolater/splitter, but that will cost me the same price as a smart new dmx dongle