Software won't let DC motor and Heater run at same time

I've found that if I try to run both the extruder and the heater simultaniously the software stops responding. I can run each part seperately and it all works perfectly fine, but when I try to run them together, the whole thing just stops responding, is this a firmware or host problem(I'm running the newest host, and the firmware from about a month ago). I'm trying to run my extruder for a long time before I install it directly. Currently it works ok if if turn the heater on, let the temperature ramp up, then turn heating off and turn on the DC motor. if I leave the heater on, the dc motor doesn't work and I can't turn off the heater element anymore either. I've search the forums but can't seem to find the answer.

Ahh what software are you running?

Reprap host software 1.0 . Which is the latest in the host directory [sourceforge.net] . It's listed as date 20081218. I've tried making it run on both linux and windows. The software runs fine on both, but it just stops workng if I try to run both of them at the same time. I'm running on sanguino if that helps.

It doesn't definitely sound like a software problem. Try disconnecting the heater or motor connections (so you don't have any power load) and just watch the LEDs. If you can turn those on and off with the software, then it's a power issue (the load of both at the same time?)
Of course, if those lights fail to turn off, then it is.

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Reprapping blog and other rants: [renoirsrants.blogspot.com]
My Reprap: [sites.google.com]

I was having this exact problem, my extruder motor and heater both work as expected independantly, but if I switch the heater on and then the extruder, the software stops responding.
Looking through the code in the extruder.pde tab, I think what is happening is the software gets stuck in a loop while it waits for the heater to reach temperature.
Set your target temp to 60 (as a test), wait for it to reach temp and then turn on the extruder to see if this is your issue.
I'm not too confident at coding, can anyone see a fix for this?
I guess maybe its not a problem when actually printing, as the nozzle will be preheated before the extruder is turned on.
Ralph

I have also encountered irregularities when trying to operate both the heater and the extruder manually at the same time. I am using the Reprap host software 20081218 on Windows XP for reference.

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[cpwebste.blogspot.com]

I've found that I can make the extruder extrude manually with this method.

Set temperature
turn on heater==>>heater turns on
wait for heater to get to target temperature
turn off heater
turn on extruder
turn on heater.

With this rather complex order, you'll be able to get the whole thing to extrude. Though this has the problem that it can make your temperature sensor routine to break down. So that you've got the heater turned on, but the temperature display gets stuck and doesn't adjust. I think that alters the loop itself, because if I leave it like this for a while my ABS can start to smoke a little because the temperature gets too high.

We also have that problem... we can't even print... how to solve this?

Ah.

Sometimes I get this: typically, though, if I turn on the heater, wait for target temp, then click extrude it works OK. I can normally turn temp on/off and extrude forwards/backwards with no problem, but occasionally the temp counter stops updating and the buttons stop responding.

Restarting the host software seems to kickstart it back to working. This suggests it's a communication error or host software?

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Reprapping blog and other rants: [renoirsrants.blogspot.com]
My Reprap: [sites.google.com]

This sounds an awful lot like the high current draw of both things is causing the voltage to wobble, disrupting comms. I'd try powering the arduino separately, or shoving hefty capacitors before each device.