JMeG Posted January 20, 2004 Posted January 20, 2004 My school has 3 Betapack 2 dimmers. The dimmers have a built-in DMX termination and we can happily link up the three for small shows etc. But supposing we need to add another DMX device after the third dimmer...Will I have to open the dimmer up and turn off (i.e. disconnect the jumpers for) DMX termination? The problem is, I don't know if the dimmers termination facility is automatic (i.e. knows if its the last in the chain) or something you have to turn on or off yourself. Any thoughts?... Jamie ;)
Brian Posted January 20, 2004 Posted January 20, 2004 On the Beta2 the DMX termination is a link inside the unit. I'd suggest unterminating all the packs and using an external termination on the last unit in the chain.
Stu Posted January 20, 2004 Posted January 20, 2004 The Betapack 2 manual says DMX TerminationEach Betapack 2 has a built in DMX termination.It is connected by adding a short wire link between?EOL? and ?DMX-? on the DMX Printed Circuit.(See Diagram 5).Connection ?CHS? referes to chassis and is unused. So this would indicate to me it's internal, so it will probably require an internal look to see if the Termination is active on your particular units. I'm guessing for 3 packs it might not actually be active, as I don't think the 6 packs in our Studio are terminated, but instead go onto a DMX Out socket in the grid (which defintely isn't terminated). However I expect a Z88 guy will post on here and let you know the official score. StuPS. Brian beat me to it! hehe
gareth Posted January 20, 2004 Posted January 20, 2004 I'm not too familiar with Betapack 2 racks, but what Stu says pretty much sums it up - pop the lid and have a look to see if the internal termination links are made. I'd second Brian's suggestion of leaving the internal terminators permanently off, and using an external one (120ohm resistor between pins 2 and 3 of a 5-pin XLR plug) when required - especially if you're sometimes going to be using extra equipment daisy-chained off the last rack and sometimes not, otherwise you'll be opening up the racks on a regular basis and that's probably not advisable (especially in a school environment). Alternatively, if you've got someone who is a dab hand at soldering, perhaps you could bring the internal termination link to a small switch on the front panel, so that you can switch the terminator on or off according to your needs? (This would probably invalidate your warranty, though, so think about it very carefully before you do it!)
JMeG Posted January 20, 2004 Author Posted January 20, 2004 Thanks for that... I could do the switch thing but for the bother of altering the dimmer (and warranty) it's really not worth it. I'll disconnect the jumpers for termination and use a 5pin term I think. I can make one up this afternoon. Ta! Jamie ;)
Eric Posted January 20, 2004 Posted January 20, 2004 Dear Sir, As the above postings have already pointed out the termination on the Betapack 2 to is internal and requiers you to put a wire link in between EOL and the - terminals. And as also state if all three were terminated I would expect to see problems.A quick way of checking is measure the resistance between pins 2 and 3 of the DMX socket, if it is measuring about 120 ohms then it will be terminated. Again as posted above the easiest thing if you will be adding other DMX products in from time to time is use and external termination.
Jambo_UK Posted January 20, 2004 Posted January 20, 2004 Could you connect the device before the two dimmer packs making it the first in the DMX chain, and then re-address the dimmer packs to counteract the effects in the change of theorder of the chain, sorry if this is wrong, ;) from Jambo Ps. Sorry for the earlier mistakes, It my rubbish English, I'm still writing in German!
Brian Posted January 20, 2004 Posted January 20, 2004 Coulkd you connect the device before the two pack making it the first in the chain, and then readdressing the packs to counteract ythe effects,Yes, as long as the devices before the packs have loop-thru outputs and do not themselves terminate the line.
James Posted January 20, 2004 Posted January 20, 2004 and then readdressing the packs to counteract ythe effects Why would you need to re-address the pack dependant on position in chain? James
WolvesAndi Posted January 20, 2004 Posted January 20, 2004 Why dont you go into the extra dimmers first and then go in to your dimmers ? leaving the temination on with out a problem
WolvesAndi Posted January 20, 2004 Posted January 20, 2004 Sorry only read half the replys before I replied, I'll get me coat
JMeG Posted January 20, 2004 Author Posted January 20, 2004 My setup is desk>school dimmers>extra dimmer>scrollers>moving lights>haze machine. It really isn't geographically practical to shove a dimmer in another position for termination purposes. Anyway, I've made a 5pin terminator now and I'll open up the dimmer and switch off it's own termination tomorrow... Thanks again everyone! Jamie ;)
gareth Posted January 20, 2004 Posted January 20, 2004 Could you connect the device before the two dimmer packs making it the first in the DMX chain, and then re-address the dimmer packs to counteract the effects in the change of theorder of the chain,With DMX, it doesn't matter what order you connect devices together - all 512 channels of information travel the whole length of the DMX line, and a unit's DMX address tells it which of those 512 pieces of information it needs to pay attention to.
Wilf dLampy Posted January 21, 2004 Posted January 21, 2004 Yes, but the termination must be at the end of the chain. Often (as appears to be the case here) the order items come in the DMX chain is affected by geography, the alternative being to run a cable from the desk, up to the lighting bars, and then back down again.(not forgetting that Longer cables can cause more trouble).
ianl Posted January 21, 2004 Posted January 21, 2004 I would suggest using a DMX splitter rather than linking through all that kit.
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