help - my first experience of DMX

[jcblincs]

OK - so I have received all our new equipment and am going to install it tomorrow. I am preparing by reading all the manual but I really cant get my head round something, Its probably really obvious but I just cant see it. I have looked on the wiki section and catn find what I need. so here I go...any qucik answers jsut to point me in th eright direction would be really appreciated.

I have bought a DMX desk and essentially 4 DMX devices (demux, 2 dimmer packs and an LED parcan). I understand how to physically connect them and I can work our how to set the addresses on al the devices. What I dont get if how I assign a DMX address to a slider on the desk. The desk is 48 channel so does that mean it will only output on DMX channels 1-48 or can I assign higher DMX channels to the sliders on the desk ?

I have got this horrible sinking feeling I have made a huge mistake with my selection of equipment and need someone to put my mind at rest please !!! The demux unit uses channels 1-72 as it has 72 outputs. I will only be using the first 12 of these. this means the next DMX device in the chain will need to start at address 73 or higher but how to I get my desk to send a control signal to the second device starting at address 73 ? the instructions for the desk are pants as they are badly translated.

I look forward to your replies. I am doing this for amatuer dramatics and as such we are all amatuers and learn as we go along. I dont have anyone to help me so I am relying on this forum !

cheers

[Davethsparky]

The demux unit uses channels 1-72 as it has 72 outputs. I will only be using the first 12 of these. this means the next DMX device in the chain will need to start at address 73 or higher but how to I get my desk to send a control signal to the second device starting at address 73 ? the instructions for the desk are pants as they are badly translated.

 

I assume this is a basic 48 way fader per channel type of desk.

All you need to do is set the address of the second receiver to 13, it's as simple as that. DMX data is not 'used up' by the receivers, you can have any number of receivers with the same address or overlap the addresses like in this situation.

I often use groups of led pars set to the same address and control them as a single fixture from the desk.

The demux will still read all 72 channels of data and take action on them but as long as you don't connect anything to the corresponding outputs then it won't affect anything.

Once you move on to a more sophisticated desk then it would be possible to patch desk channels to any address you want.

 

Unfortunately this is the price you pay for going down the budget equipment route, no training and dodgy manuals. Did you buy this over the internet? Or did it come through a real-world lighting company?

[gherriott]

Could you tell us the make and model of the desk? This will enable us to best help talk you through how to patch it to your needs.

[pritch]

It would help a little if we knew what desk it was; some might only work up to channel 48, others will let you patch to the entire range of 512 channels. However, don't assume that just because your demux has 72 channels, it'll keep those channels just for itself.

 

If, for example, you set your demux to channel 1, then the demux itself would respond to channels from 1-72. But if you only had dimmers connected to outputs 1-12, then those are the only ones that would operate. There's nothing to stop you putting your next lot of dimmers onto 13 onwards.

[jcblincs]

guys - thanks so much. I think I get it now...

I have a showtec demux and a showtec 48. I am now realising that the showtec 48 cannot be soft patched. I bought everything in a hurry - I know this is not ideal but circumstances have intervened and thats what I am stuck with !!! I bought all the gear from 10outof10productions. they were very helpful but I think that I didnt explain everything completely to them !! I am doing this for my local am dram society and we only do this as a hobby and do it once a year - everything I know I have learnt from experience as there is no-one else vaguely technician in the society - they are all arty farty types !!! ** laughs out loud **

 

anyway - back to business...

I only need to control 20 lighting channels plus an LED parcan that uses 6 channels so the fact that I ahve a 48 channel desk is OK. From your replies above my understanding of the situation is now this...

 

1) set start address of demux to be 001 (uses 001 - 012)

2) set start address of 1st four channel dimmer to be 013 (uses 13-16)

3) set start address of 2nd four channel dimmer to be 017 (uses 17 - 20)

4) set start address of LED parcan to be 021 (uses 21-26)

5) demux will output on channels 1-12 , which are connected to our existing 12 channels of analogue dimmers

6) demux will output on channels 13 - 26 but as these are not physically connected to anything it doesnt matter

 

can you confirm I have understood correctly ?

 

I know that the showmaster is an el cheapo desk and I now realise its limitations. However if the above is correct I think I will be OK

 

cheers

[pritch]

That's pretty much it, yes.

[Davethsparky]

Yes, you've got it spot on there.

From an operators point of view I would be inclined to set the led par to start at 25 so that it is at the start of the second row of faders making it easier to find and seperating it from the dimmer channels. This is only my personal preference for working with a set up like this, you may find it works for you.

When it comes to marking up the desk you will find that white insulation tape is the best thing to use, don't use masking tape because it will leave a horrible sticky mess on your desk.

 

Can I also suggest you look up ujjals DMX page on the net and have a read through it, you may find it useful in understanding DMX.

[jcblincs]

thank you thank you thank you !!!

 

I spent 30mins looking up articles and getting more and more convinced I had screwed up big time !!!

 

you have just saved a sleepless night !!! I was working out how to tell everyone I needed to spend loads of cash on a better desk so I coudl cross patch.

 

In a strange way I think things will be less confusing this way round.

 

if I could buy you all a pint I would !!!

 

this forum is ace !!! and it helps that all technician people are nocturnal and have nothing else better to do on a fridy night that help out a muppet who didnt have time to do all his technician homework !!!

 

all I have to do is wire in the demux and desk tomorrow and test it all out. then I have to decipher the badly translated instructions for programming the scenes up on the desk !!

cheers everyone

 

A concurrent post has been automatically merged from this point on.

 

Can I also suggest you look up ujjals DMX page on the net and have a read through it, you may find it useful in understanding DMX.

 

thanks !! googled it and found it straight away...I shall read it before I go to bed !! cheers

[tom_the_LD]

Just a little side note which is not strictly related to your original post.

 

I've had a mini demo and play on the showtec 24 (the smaller version) and the dimming on it was awful. With the fade master set to 0, when you pushed up the preset to bring up some lights it was all jumpy and horrible. Not smooth at all.

 

So, see what it's like, but you MAY want to send it back and swap it for a different desk.

[jcblincs]

well - its all installed and working !!

had long day but it was worth it as its working really well. gone from the old set up with a limiting 12 channels - 6 on stage and 6 front of house to now 8 on stage, 8 front of house + 4 spares to be used for foot lights/dresign room call lights/chandelier on stage. Plus an LED parcan for colour wash behind an opening door.

It really was a doddle to set up thanks to all your help last night. The only issues I had were the incorrectly wired DMX patch leads (Grrrrrr - ordered pre-made cables to save me a bit of time and ended up getting the soldering iron out as two ofthe females XLR plugs had been wired the wrong way round !!!!) Luckily I guessed the leads might be dodgy after only 5 mins of head scratching.

 

The showmaster 48 - to be honest I am impressed. Bear in mind I ahve never had DMX before and the abilty to set and store scenes is a huge bonus. I know its not the best deskout there but for £250 I think it is very good. No issues with the fading.

 

Most of my time has been taken up with rigging / hard patching and routing cables through the loft to make a better job of it. The cables that were already in the loft actually did work but , due to the advice given in some of my previous posts, I elected to lay a new, proper DMX cable.

 

the only thing I havent done is put a resistor at the end of the chain. Doesnt seem to matter as it all works but for the sake of a plug and a resitor I will do it. couldnt find a 0.25W resistor, only 0.5W (does it make any difference ?) so had to order some from RS !!

 

WELL - enough of me waffling on !!! THANKS AGAIN TO ALL OF YOU WHO GAVE ME ADVICE - its much appreciated. I am very pleased with our set up and think we did well - desk £250, Demux £180, £150 for 2x4way dimmers. Lots spent on cables and connectors or course. but for £1100 we ended up with 20 channels, a DMX desk and an LED parcan.

 

cheers !