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Hello Oliver_74 You can use the Add as additional address function found in the Edit DMX Address window to pair your five fixtures. When you select the DMX address of the first fixture you want to pair, the curser will flash in the DMX address window which will be blank. Type in the address of the second fixture in the pair, select Add as additional address, then Enter. The Fixture schedule window will show two addresses for the channel fader of the first fixture. I only found this last week when I wanted to pair dimmer channels under one fader.

I finally got a chance to try this yesterday and it worked! (A latched submaster with colours set to zero on affected fixtures.) Oddly, a few MFKs initially didn't work with it (either not coming up at all or affecting other lights they hadn't affected before) and I could find no difference at all between the ones that worked and the ones that didn't. But re-recording the ones that didn't work fixed them so I was happy.

An ohmmeter won’t help you. The cables don’t have a different dc resistance they have a different ac impedance. The most practical way to tell is from markings on the sheath of the cable that will tell you it’s ’DMX’ or ‘digital’ cable maybe. If it says ‘microphone cable’ it’s not really for DMX use. You can use ‘DMX cable’ for microphones but ideally not ‘microphone cable’ for DMX. (My response coincided with David’s posting, I’ll read that now!).

So now you are into something of a grey area - I fully expect this response to attract comment. It especially needs comment from a sound tech as I'm hazy about that side of things. You can often get away with audio cables for DMX but no-one in their right mind would recommend that because you might not get away with it and you can bet the problems would only be apparent mid show and not at fit-up. The easiest way to tell the difference is to see if it is printed on the cable . 150ohms is not the resistance of the cable it is the impedance. Cables do have a resistance but it is dependant on length and is only important if the cable is meant to carry a current (as in mains cables where it is very important and is part of PAT testing). As far as I can tell from researching it, DMX cables should have an impedance of 150ohm as you said). 110ohm is allowed but not recommended. I'm guessing, but I suspect anything below 110ohm is likely to cause problems. The standard for audio is 110ohm but there is a wide range in use - 60ohm to 150ohm is quoted. Apperently, the main thing for audio is that the source and cable should be low impedance and the sink should be high (e.g. 10,000ohms). I Googled "what is the correct impedance for balanced audio cables" and read the AI response to get this information. This would suggest that a "standard" impedance audio cable would be acceptable for DMX but the really low (below 110ohm) cables would not. You can measure the impedance of cables with the right equipment but you can't use the resistance range of a multimeter. Google "how to measure the impedance of a dmx cable" for ways to do it. Your physics lab techs might be of help in this area. Ultimately it is better to keep your audio and DMX cables apart and mark them with something obvious so you can put them away properly. (That's a big ask in a school I know.) There is a reason why the standard for DMX is 5pin XLRs even though it only needs 3pins and 3pin XLRs are cheaper.