FSBUS Noice/Interference HELP!?

[olealm]

Hi!

Sorry, my deutch is not what it used to be

I was connecting the FSBUS Interface modules of the 737NG
Pedestal today and was DISAPPOINTED! Have the COM board behind he
MIP and 2xDisplay/1xLED/1xKEY inside the pedestal box. The cable
connecting the pedestal interfaces with the COM board is shielded
and I have connected the shield to ground on the COM side. All
other cables are ordinary flat-cable.

Problem is that there seemes to be lots of electrical noice in
the "system" when I connect the bus cable (apporx. 1.8m long)
connecting the COM and the pedestal interface boards.. Have a
FSBUS Key interface in the MIP section also and that seemes to be
affected also (the test function shows lotsa quick signal
changes)! In addition the relatively short cables from
buttons/rotaries to the Key board (both are inside the pedestal
box) creates lots of "noice" also (in the test function for the
pedestal Key board typically turning any rotary will generate
on/off signals for all buttons in that row.

The Key Interfaces are CID 1 and 2.

All in all a big disappointment!!

Question is: Is there anything to do to fix this ??
What Interface solution are you guys using and have you had similar noice problems ?

Please dont tell me all the interface work/expences was in wain
and that I have to go for a different solution...

[dirkan]

Hi Ole,

cable length and interference problems may occur, the longer a cable is. But before you throw anything away, try out what the real problem is.
If you say, any key of a row is affected by a single button press, there may be something very misterious.

I suggest you to remove all cables from the interfaces and then connect one after another and look what happens and when the problems begin.

You can add resistors to make the key inputs more insensitively. But before i tell you how, be sure where your problem is. Attach some photos of your cabling.

Good luck

Dirk

[olealm]

Hi Dirk!

Thanks for your quick answer!

Well, after working all night I finally found the source for the noice. It was the 24V PS for the Simatic PLC (which is controlling the power-up of the computers and ATX PS's)! Had it mounted in the MIP, but tried moving it approx. 3-4 meters away but still made the FSKey go bananas. Changed it for another 24V PS and VIOLA - problem gone. Have only tested 1 rotary and a couple of switches for the pedestal FSKey and that looks good so far. The MIP FSKey also looks free from spikes.

It took the whold night, but boy was it worth it!

Really sorry for making my frustration make me question the quality of the FSBUS design !!!

Pictures:
The bus cable connecting MIP COM with pedestal Key, LED, 2xDisplay:


Key and LED (pedestal):


COM and Key (MIP)


DOs (MIP):


The trouble maker!:


While Im at it I have a few questions:

- Can I use 12V from one of the ATX PS's instead of the specified 9V ?
- Read somewhere that if I connect a rotary to SID 0 and 1 I cannot use pin 2 and 3 for ordinary switches, is that correct ?
- Think the CCC have a few bugs (getting divide by zero and some other stuff), will there be more developement of the FSRouter ?

Again - sorry.

[dirkan]

Hi,

i can imagine the feeling and frustration after a night of work.

But now to your questions. Of coarse the development is continuing. The CCC is in an early beta state as i mentioned in the download page. My current version is morer stable and has some new things like connection points between different CCC objects.
When its ready, it will be downlodable as expected. I am now rebuilding my cockpit to make it moveable (in car). This gives the chance to improve some things and test it in practice.

But keep in mind, a good cabling is important to have a reliable stable electronic. Not only bad power supplies may trouble you, also ordinary lights and mobile phones may cause problems.

I have tested some improvements by 8 additional pullup resistors at each port. I tested 3,3kOhm, but its to early to make a final recommendation. I will spend some hours flying and see how anything works.

regards Dirk

[dirkan]

i forgot:

- the 12V is not tested but may work. Keep an eye and a finger tip on the 7805. It may get hot!

- the usage of sid0 and not the other ones is a big which is fixed but currently not in download area, but it will be.

regards Dirk

[olealm]

Hi!

Good to hear the developement is ongoing. Read smewhere in a forum that you are a very busy person, sp I was afraid all your resources were used in other areas.

As for the 12V I tested it and the 7805 cooling ribbon got VERY warm.. could only take 1-2 sec. before I had to remove the "detector finger". Think Ill stick to the 9V adapter to be on the safe side.

Thanks for yor answers!