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MIDIO128 question


jwillans
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Hi,

I am new to this forum and am planning a church organ midification project which I think Midibox will be ideal.  I have done a fair bit of forum searching and reading, I think midio128 is probably the key module for me.  My question is, what if my organ has > 128 outputs?  Is it then necessary to use a further core module-midio128 (multiple DOUTs) combinations and link together using midi-thru?

Many thanks for the info and great project.

James

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My question is, what if my organ has > 128 outputs?

i have read on this forum about work on implimenting a scanning matrix so that more inputs can be read.  the downside of this technique is that input latency is increased from around 1ms to 8 ms.

Is it then necessary to use a further core module-midio128 (multiple DOUTs) combinations and link together using midi-thru?

i think it would be better to connect 2 or more core-midio128 in a daisy chain.  you will probably have a lower latency than a scanning matrix.

additionally midio128 can be setup to recognise the difference between a passed through midi in signal and a midi out from further up the daisy chain. (sorry, but i don't think this is reading the way i mean it) i believe it is done with the configuration file, but i don't know exactly how.

 

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I have successfully midified my organ, 3 manuals, pedal, stop tabs and pistons, using three cores. The cores are chained using standard Midi cables (Midi Out to Midi In).

Is it then necessary to use a further core module-midio128 (multiple DOUTs) combinations?

You should use DIN's since I assume that you are midifying the keys and pedal. The DOUT’s are used for controlling LED’s, relays or similar.

I do recommend using the standard MIDIO128 because it’s tested and proven very reliable with a minimum of latency. It also very flexible, you can mix key contacts, pistons, and different Midi channels all on the same core.

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  • 2 weeks later...

I'd be grateful for some more info describing strategies for chaining multiple core modules running MIDIO128.  Is it as straightforward as connection midi-ins to midi-outs?  Presumably the software is configured for cores so that midi data is unique, for example core1 to send data on channels 1 and 2 and core2 to send data on channels 3 and 4?

Thanks,

James

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Is it as straightforward as connection midi-ins to midi-outs? 

Yes. Be sure to have the MIDI Merger enabled in the MIDO128 INI file.

Regarding the channel assignments there are no limits. You can for example send MIDI commands on channels 1, 2, 3 from Core 1 and from Core 2. It's only dependent on the configurations in the INI files. There will be no mix up.

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  • 2 weeks later...

I'm still confused about using multiple cores for the MIDIO128.  What is J11 used for if all you need to do is daisy chain the midi-in to midi-out and activate the midi-merger?

I'm midifying an old Hammond organ with two 61 keyboards and one 32 key pedalboard.  I will have second touch on all keys and pedals so I will need 3 or 4 cores depending on what I do with the presets. ???

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If I have three cores, do I conect the core-0 J11 to the core-1 J11?  Do I have to reversethe two wires between MI and MO?

Also How to I connect the third Core? Do I also connect it to core-0 J11 or core-1 J11? ???

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A Word of Caution No 1.

I completed my Church organ recently.  You have to be careful with the cable length between the core and the Din and also between Din and Din. The output of a Din is not a line driver with matched impedance.  I had to mess around a bit to avoid cable length problems.

I have used Core 1 with 4 Din modules for the the Swell and Great keyboards.  I mounted the core in the upper keyboard.

I have used Core 2 with 3 Din modules for the console and the pedals.  Core 2 is mounted in the console. Din 3 is for the pedals and is mounted near the pedal switches

The above arrangement works but I have some interference. 

I would recommend that you consider having an additional core 3 with 1 Din.  The core can then be mounted close to the Pedal Din near the pedal switches.  All this means is that the Midi signal paths are longer which is not a problem.

Word of Caution No 2

I started my project using Midio 128.  Everything was fine until the Manual/ Pedal  coupling was required.  I then found that the Midio 128 application could not handle this aspect. I can explain this in more detail, I think.  It was about 3 years ago.

The result was that I had to start again programming my own application in C.

If Manual/Pedal coupling is needed, work out what you need to do in advance.  In your case things may be OK

Regards Robin

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Hi Robin,

Many thanks for the tips.  I will take care to consider Caution 1, could there also an issue with the cables length between the din and the keyboard contacts?  Since co-locating the din(s) and the core(s) will necessarily increase this cabling length.  I don't think your second tip is relevant to me since all coupling is done in software.

James

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I haven't done enough with DIN boards to give an answer tempered by experience but based on analysis I don't think the length of the connection to the key switch inputs will be a problem. The cabling between DINs and to the Core carries all the 128 inputs on a single wire and the clock signal to make that work. You are dealing with fairly high frequency signals on that cable. The inputs are essentially DC signals.

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I have not had any problems with cable length.  I suspect any problems in this area are caused by some other problem.  My project has 4x DIN to CORE1 and 2x DIN to CORE2 with the cores connected via Midi merge so only 1x Midi input to the PC via USB.

I have still not finaliased the position of the CORE PCB's so have experimented on the floor and in the upper console and one in each position.  I have 2m and 3m long cables from DIN's to CORE's.  My current arrangement for CORE2 has a DIN in the upper console connected to pistons, this connects to the DIN on the floor for the pedals and this then connects back to the CORE2 mounted back up under the lower keyboard.

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I forgot to mention that the problem the console also involved Dout modules.  This comprised Core  plus 2 Din plus 2 Dout behind the console then another Din for the Pedals located in the pedal switch assembly.

The Dout and Din both load SC and RC.

I shortened the cables to resolve the problem.  The problem I recall was interference on the Console Led's which are driven by the Douts.

Robin

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