Nsi If501


My church has an older CD80 pack (AMX only) and Mantrix board. For our Christmas program I'm trying to set up to run off a laptop so I can do a cue list instead of running manually. We've bought an NSI IF501 and an Enttec Open DMX USB unit. We also bought an NSI 808CP to use as a day-to-day controller. According to the documentation I should be able to use both the DMX and the Lumanet controls at the same time, but nothing's working right with these controls at this point.

With the Mantrix board everything works OK. With the Enttec, running Stage Console, the lights on a channewl are dark until the fader is at about 50%. Noticable flicker at low levels. Slow movement of the fader gets to max brightness at about 80%, then holds at max the rest of the way up. Fast fader movement with the mouse or a timed cue change causes seemingly random flashing, and the lights go dark at about 80% on the way up and stay off above 80%. The 808CP at "off" gives about 30% light level at all fixtures. Going to manual mode the sliders seem to work OK, but 0% slider setting is still around 30% light from the fixures. These tests were with just the controller being tested connected.

I've checked and cross-checked the jumpers, and they're correct as far as I can tell. I've also ohmed-out the cables. There's a chance the 808CP is bad -- it was bought as new, but it's obviously an open box return (shipped directly fron the vendor, but there's a UPS label still on the box showing a drop shipment from Leviton to an address in the midwest). This could also be me mis-reading the documentation -- it's not nearly as complete as the engineer in me would prefer.

Any suggestions on what to look for would be appreciated.

HI Martin

Oh BOY are you in for fun. I have a if501 and a pathway connect that we use if we need to do some conversions etc. Honestly it is a nightmare.

The problem is that AMX is analog but it has this wierd sync system that is very sensitive to the cable, and the dimmer interface and its age and how the components have aged etc. So it may work great with your mantix, but when you add in the IF501, you have a device that they basically designed the sync sort of for the average tiiming system, sometimes you are lucky, most of the time you are not. I don't think you are doing anything wrong. It is simply a case were the dimmer pack sync spec and the CD80 don't quite match up, and AFIK the nsi unit is not tweakable. I am sure you have looked at the jumpers uudu p7 off etc

Doug Fleenor http://www.dfd.com/2amxdata.html
Doug really knows his stuff, but it is not cheap.

Pathway Connectivity http://www.pathwayconnect.com/content/view/32/29/
I have one of the Ultimate units, better than the NSI but still not fool proof

IMO The only thing that really works reliably here is to convert the cd80 directly to DMX where the old amx interface is removed.


Probably not what you want to hear, but ...

Thanks for the quick reply. It looked like a timing issue to me, but I don't have the AMX192 spec, and I don't think I have time to order the spec from USITT with the program 2 weeks away. That leaves me with re-building cables and having another set of eyes look at the jumpers as the available options.

I looked at dfd.com and pathwayconnect.com before deciding on the NSI converter. Part of the deciding factor was cost, and part was the need for an architectural control station for the staff who are not comfortable with a full console. With the budget thoroughly busted already I pretty much have to find a way to make this work or go back to the Mantrix.

HI Martin
The problem is the NSI unit does not have afik any way for you to alter the timing. Basically, and I am not an expert but more a victim... the amx192 uses an imbedded clock like RS425 (like martin used). this is different than the system Strand eventually went with in the UK which had a sep clock.

I agree it is a timing problem, what you have is the transmitter uses a wide window clock, and the receiver at the dimmer is set up to have a narrow window so that it can detect the widest variation in clocks

Don't know what coast you are on but Strand in LA is 800 478 7263 and NY 212 795 3043. There is a reason why the other units are more expensive, typically people buy the NSI it works or it does not, and if they need to they move up to the other units.

Not sure how you have it hooked up, are you putting the converter right by the dimmer or back by the controller? If you are technical and have access to a scope I am sure you could look at the sync pulse timing, but not sure if there is a way to adjust it on the CD80, strand could tell you. As these packs age, the reading window probably drifts a bit.


So far I've worked out the interface problems between the 808CP and the IF501 -- works fine if I remove the termination jumper on the 808CP. That much I could do at home. The rest will have to wait a few days. The IF501 sits on the dimmer. The console (actually laptop with USB to DMX converter) is within 10', but the DMX cable I have is 50'. I'm thinking that the problem on the DMX side may also relate to termination.

FWIW, I'm a licensed/registered professional electrical engineer. That may be part of the problem: the manuals are just connection instructions, but I want/need to know WHY and HOW it works.


Ok, just to make sure things are set up as best as possible

dmx uses a special cable, 110ohm and needs to be terminated, most people also recommend a twisted pair in the cable. I my experience the termination with a 120 ohm resistor across pin 2-3 is more important than the actual cable, but some people argue differently.
Basically what happens is that if you don't have a terminator you get reflections of the digital signal, and this "noise" interferes with the signal.

The final device in the chain would need a terminator, so if you go console/pc unit to the 501 the 501 would be terminated. You need to be a bit careful in this setup since DMX controllers are sensitive to getting a voltage back to them which is why opto isolators are typically used. So for instance if you were to plug your amx line directly into your dmx controller by mistake, you could cause problems. Typiclally this is not going to happen since amx is 4 pin and dmx in this setting is 5 pin. (you have a 15v signal on the amx side of things)

All of these analog systems have potential problems since they work by sending all the data for all the devices out as pulses and you have to clock them to detect first that the signal is for your device, then for your channel and then the level you need, so clocking is really the problem.

This is why before they went to dmx there were attempts to get the clocking off to a different connection. (strand had d54)

AMX192 is really an extension of RS485


This is not exactly how it works but will give you a lot of the nuts and bolts, as I said earler, Strand Martin all basically used a varient of rs485 and then implimented their own protocal on top of it, but the signals and how it works I BELIEVE are pretty much the same. This will help you get more information.

I am willing to bet the problem is the link between the 501 and the CD80, the Cd80 is "looking" for the clock and signal and not being able to cleanly detect it so it gets "confused" miss reads the signal

In case anyone is interested, I have most of the bugs out of the system. The primary problem was in the IF501 -- the unit uses insulation displacement connectors to hook the DMX connectors to the circuit board, and one of the wires (signal common) wasn't making proper contact. Easy to find once I figured out what the AMX signal was supposed to look like.

Now I just have to get the Enttec Open DMX adapter working....


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