Expansion options via unused ports

[Luis Fraguada]

Hello!
Now that my mechanical frame is moving thanks to help from others on this group, I need to go a step further to finish the electrical system.  I want to drive a solenoid valve that is rated 24v 4w.  This is the valve: http://www.buerkert.com/COM/search.php?type=6012&SearchText=6012

I have been able to run this valve on a 24v system with 2A going into the system.  For now, I am trying to do this without modifying the firmware.  I have hooked it up to the extruder fan pins and if I go into the replicator g control panel, I can click on the fan enable check box and get a slight response from the solenoid.  It seems that there is not enough current going to these pins to actually power the solenoid.

What are my other options?  I am not using the Extruder Driver, Heated Bed/Temp, or Extruder Heater / Temp ports.  Could I drive the solenoid from these?

I have explicitly chosen the R2C2 platform to experiment with ARM platforms.

Thanks in advance for your advice!

Luis

[Francisco Mendes]

On Tue, Jul 30, 2013 at 12:41 PM, Luis Fraguada <frag...@gmail.com> wrote:

Hello!
Now that my mechanical frame is moving thanks to help from others on this group, I need to go a step further to finish the electrical system.  I want to drive a solenoid valve that is rated 24v 4w.  This is the valve: http://www.buerkert.com/COM/search.php?type=6012&SearchText=6012

I have been able to run this valve on a 24v system with 2A going into the system.  For now, I am trying to do this without modifying the firmware.  I have hooked it up to the extruder fan pins and if I go into the replicator g control panel, I can click on the fan enable check box and get a slight response from the solenoid.  It seems that there is not enough current going to these pins to actually power the solenoid.

The fan output have a current limitation of 100mA. 

What are my other options?  I am not using the Extruder Driver, Heated Bed/Temp, or Extruder Heater / Temp ports.  Could I drive the solenoid from these?

The power outputs where developed to operate resistive loads only. 

I think that shouldn't be a problem if you connect a low inductive load and use a fast diode connected on the terminals of the valve. 
The R2C2 have a protection diode on each CTC output but using one close to the load should be a good guaranty that you don't kill the mosfet.

This diode is connected between the valve terminals. You need to check the polarity. With voltage applied to the solenoid the diode shouldn't conduct!

I have explicitly chosen the R2C2 platform to experiment with ARM platforms.

Thanks in advance for your advice!

Luis

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[Luis Fraguada]

Hello Fernando,
Thanks for your reply.  Actually, the valve can be actuated just fine via the Fan Port (also from the extruder, but I would need to change significantly the gcode).  I hooked up the pressure source to the valve and it works just as expected with M106 and M107.  I guess though, this is not healthy for the R2C2?  Unfortunately, I do not know how to do what you mention in your reply.  Which diode do you recommend?  How fast can it actually be?  The diodes I am used to are quite slow in relation to the necessary actuation in the gcode.  Are any other components necessary besides the diode, the valve, and some cables?

Thanks!
Luis

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