How to center pneumatic cylinder

[TheAmunraaa]

Hey!

Jumper was different but computer caused problems...anyways that's fixed *
There is another problem that occurs every once in a while.
Simulator works fine when all of a sudden converter stops sending forces from math to Velleman k8055 and sets outputs 02, 04 and 06 to 100% which causes our simulator to extend all 3 cylinders. Then a restart of converter is needed to clear outputs so we can manually lower the simulator. We have been looking at math outputs and there is no defined state where it happens. It appears as if our computer "loses" connectivity with our control board. Also our cylinders are centering themselves, but while doing that they are moving a lot (~5cm in both directions). Is there any way to fix that.
The problem is visible here:
https://www.youtube.com/watch?v=XhqOSCkpfdg

Kind regards, Aleksander

[sirnoname]

I am sorry, without informations like the rn2 file and a drawing of your wiring with air and velleman it is impossible for me to help you.

[TheAmunraaa]

I am sorry, without informations like the rn2 file and a drawing of your wiring with air and velleman it is impossible for me to help you.

Ok! I'll post them here tomorrow, because we have no wiring drawn yet.

[TheAmunraaa]

I have drawn rough scheme of our wiring. I have not drawn all 3 pneumatic cylinders and all 3 pots but valves are all connected the same way. Each 5/3 valve has 2 connections from the k8055 #1 board and negatives are connected from one negative wire. One pot is connected to k8055 #1 and the other 2 are connected to k8055 #2. Power for pots (5VDC) comes from molex connector in our computer.

We have tested for the bug many times and the results are:
80% of the time it stops working at around 4 minutes and 20 seconds
10% of the time it stops in less than 1 minute
5% of the time it works for around 17 minutes
5% of the time it works for more than 25 minutes

I have uploaded wiring scheme and rn2 file that we use.

[sirnoname]

I don't understand your 12VDC power connected and there is no GND connection between the amplifier and the velleman.
Please double check your drawings.

The rn2 file seems to be ok for me.

Did you try it with only one K8055d connected?

The problem is visible here:

I cannot see it, plz tell me the time where I can see it.

Generaly if there is a nice voice which say that a interface is disconnected you have a USB or GND problem with your board.
What happens if the board looses the connection? A messagebox, a warning, a converter hangup or freeze?

Can you reproduce the hangup if no simulator hardware is connected, i.e. will the reproduction work if I only connect a velleman with your rn2 file and let it run a while or do I need to have hardware attached?

Take the time and try to answer all the questions for a faster help.

[TheAmunraaa]

Sorry! I posted wrong video. Here is the right one: http://youtu.be/aOG_22j7k58?t=28s
We have not tried with one k8055n attached because we loose 1 or 2 ref pots in that case.
When it happens we get no messageboxes, warnings or voices. Converter doesn't stop or crash. Only thing that happens is that it sets on every other (02, 04, 06) output, and then we have to close Converter and start it again to clear outputs.

If we disconnect velleman boards we get form (Exchange dialog) where we have to assign outputs and inputs to the board. But this has never happened while running.

About connecton with k8055 #1 and 24V amplified board:
-this is a board with 8inputs and 8 outputs
-on input side we connect +12VDC and the -12VDC is connected to k8055 #1
-on the output side we connect +24VDC and -24VDC
-we get 12VDC and 24VDC from conventional AC/DC power adapters
-board is made by a professor who didn't exactly explain how it is made


edit: we haven't tried with hardware detached yet

Please excuse my poor explaining and my broken English

[sirnoname]

I did never use such boards, the ULN2803 on your velleman is able to handle 24V, no need for a opto element. Perhaps your relais need much ampers and you need this electronic. -12VDC seems to be wrong named, call it GND, else you have 24V on input and 48V on output.
If all is expanding it looks like to me that the velleman is setting all outputs to high. This is a reset situation. A reset can be a USB disconnect or influence to USB or a overpower situation.
To get a clear answer you need to run the velleman without any other hardware connected for a while (playing with the pot).

[TheAmunraaa]

Thanks for the explanation!
So we can hook 24VDC to velleman and run wires directly to valves? We have this board because we feared that we would fry velleman with 24VDC.
Do we need any relays or transistors between valves and velleman if we connect 24VDC directly to velleman?
So far we haven't had velleman disconect so it looks as overpower situation.
Will port results when we get to test simulator again.

[sirnoname]

So we can hook 24VDC to velleman and run wires directly to valves?

That you have to find out with the datasheet of the ULN2803 and the power consumption of your valves. My RnR valves take 50mA per valve.
If this chip get deffective you can insert a new one. It like a fuse for the microcontroller chip.