LTC module works intermittently

[sidetrack]

So I have my optocoupler out of the core module and my max232 stuffed.  I can load up MIOS studio and link the ports to the yamaha CBX driver, I receive information coming in from the box just fine.  The ltc module ceases to communicate with the computer a few minutes into using it in ableton.  The in and out led's still function but if I reload MIOS studio, The connection from the yamaha cbx driver to the MIOS IN port is now a dotted line.  So it is unconnectable. 

A restart of the computer seems to fix this, and the communication stays constant so long as I am in MIOS Studio.  I have done a few tests in ableton and MIOS studio.  I found that the pots appear to all be switching channels during their rotations.... which never happened when I was using midi cables.  I also found (in ableton) that If i do not assign the cbx driver output back into the midibox, the communication is not interrupted.  It seems the problem originates as soon as ableton attempts to send midi information to my midibox, a few minutes after it tries doing this it freezes up and no information is sent either way. 

Leaving it with just the midi in is fine, but the pots are jittery as hell for some reason, and they were not jittery at all when I had it hooked up with midi cables (and the optocoupler in).  It seems odd to me that I cannot see this jittering on my LCD display, it looks smooth and fine on the lcd.  So, any help is welcome, as I currently have no idea what is happening.

Note: I have been using the midibox with no problems when it is hooked up via midi cables, the modules that are installed are the core, LTC, AIN, LCD and DIN.  When I was using it with the midi cables before I had left the MAX232 stuffed as well as the optocoupler, I only recently realised that I should remove the optocoupler if I wanted to use the midi to com connection.

thanks,

Ryan

[TK.]

Hi Ryan,

sounds like a windows driver issue - a friend had a similar problem with his MIDI interface, it also locked up when heavy MIDI traffic was sent (or received). Fortunately there are two other RS232 drivers available (Roland and Kawai) - did you try them also?

Jittering pot values are a general problem when the circuit is not galvanically decoubled from the PC, therefore for MIDI an optocoupler is normaly prefered. Does anybody know some measures, how to reduce the additional noise? I'm not an analog expert... (please write this into the Wiki)

Best Regards, Thorsten.

[sidetrack]

I had tried the Roland drivers as well, but that was before I knew that the optocoupler was supposed to be removed.  I'll try this again and post my results. 

If I leave in the optocoupler would this create a short?

[sidetrack]

So, I cannot get the Roland drivers to work at all, and I have no idea how to install the kawai drivers.  It comes with no documentation and just a dll file.  I dont know where to put it, the file appears to be an executable but whenever i double click it, it unzips it to a folder.....

Anyways, so far no go. 

I think if putting the optocoupler back in will fix the jittery pots, then I will be able to use it, I just wont assign ableton to send information to it.  However in the ucapps documentation it says that having both the optocoupler and the max232 stuffed will cause a short... if this is true then have I already shorted out my ltc module??? because I had both installed before when the box was powered up. 

Ryan

[TK.]

However in the ucapps documentation it says that having both the optocoupler and the max232 stuffed will cause a short...

thats correct. In theory you could use optocouplers for the Rx/Tx line of the MAX232 in order to decouble the PC from the core module, but I cannot give you a schematic for this, this would have to be worked out by yourself.

if this is true then have I already shorted out my ltc module??? because I had both installed before when the box was powered up.

Thats interesting, this might explain why the driver hangs up? Maybe because an incomplete event which was received due the "shortened" Rx line (sidenote: it's not completely shorted, because the optocoupler output is open drain - but the signal level at the Rx input of the PIC will be lowered).

So - does it work more stable without the optocoupler, then you found a solution. If not, the RS232 link just doesn't work quite well with your PC, and either the LTC circuit has to be enhanced, or a common MIDI connection has to be used.

Best Regards, Thorsten.

[sidetrack]

Well the midi connection works just fine with the optocoupler out.  So it would seem that the ltc module might be diminished.  I think I am gonna have to look into enhancing the LTC module.

Although I have no idea how to do this, I'm off to the forums to see if there's any info on it!

thanks TK

Ryan