Cutting power by software - what device do i need?

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diep
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Cutting power by software - what device do i need?

Post by diep » Mon Mar 19, 2012 8:54 am

hi,

My chessprogram runs on a box that uses a switch that doesn't have a 'power off' button.

This mellanox switch however, you can see from my facebook pictures there (my entire facebook is open to the entire world to browse), it produces 75 decibel or so and i sit a few meters away from it.

Now i got rid of the fans from the switch and replaced it by cardboard and big outside fans. Where the psu can give power to 1 fan that cools the psu (hopefully it'll go ok as the airpressure of the fans i use isn't that high), the other 3 fans from the case do not have this luxury solution. The easiest solution is use an external adapter.

This external adapter could break at which point a disaster might happen to the switch. From 1 of the motherboards of the box i can easily monitor the RPM of the external fans. If one of them drops to near zero, which would happen for example if the adapter breaks, then i want to give the controlling proces there the order to cut the power of the switch.

Writing the software i'll manage, but what device to use that i can control by software or maybe even a simpler solution is there.

Note that i do realize this is not a 100% solution, yet the odds that one day the 12 volt adapter breaks is there, so i want to catch THAT possibility.

I feel some cheapskate solution probably exists. Any thoughts on how to solve this i welcome.

bob
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Re: Cutting power by software - what device do i need?

Post by bob » Mon Mar 19, 2012 4:46 pm

diep wrote:hi,

My chessprogram runs on a box that uses a switch that doesn't have a 'power off' button.

This mellanox switch however, you can see from my facebook pictures there (my entire facebook is open to the entire world to browse), it produces 75 decibel or so and i sit a few meters away from it.

Now i got rid of the fans from the switch and replaced it by cardboard and big outside fans. Where the psu can give power to 1 fan that cools the psu (hopefully it'll go ok as the airpressure of the fans i use isn't that high), the other 3 fans from the case do not have this luxury solution. The easiest solution is use an external adapter.

This external adapter could break at which point a disaster might happen to the switch. From 1 of the motherboards of the box i can easily monitor the RPM of the external fans. If one of them drops to near zero, which would happen for example if the adapter breaks, then i want to give the controlling proces there the order to cut the power of the switch.

Writing the software i'll manage, but what device to use that i can control by software or maybe even a simpler solution is there.

Note that i do realize this is not a 100% solution, yet the odds that one day the 12 volt adapter breaks is there, so i want to catch THAT possibility.

I feel some cheapskate solution probably exists. Any thoughts on how to solve this i welcome.
This linux, windows, or some other custom o/s???

In linux it is pretty easy to write a shell script to access the lm_sensors info, and if a fan's rpm drops to some chosen value, shut the system down quickly...

diep
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Re: Cutting power by software - what device do i need?

Post by diep » Mon Mar 19, 2012 6:06 pm

bob wrote:
diep wrote:hi,

My chessprogram runs on a box that uses a switch that doesn't have a 'power off' button.

This mellanox switch however, you can see from my facebook pictures there (my entire facebook is open to the entire world to browse), it produces 75 decibel or so and i sit a few meters away from it.

Now i got rid of the fans from the switch and replaced it by cardboard and big outside fans. Where the psu can give power to 1 fan that cools the psu (hopefully it'll go ok as the airpressure of the fans i use isn't that high), the other 3 fans from the case do not have this luxury solution. The easiest solution is use an external adapter.

This external adapter could break at which point a disaster might happen to the switch. From 1 of the motherboards of the box i can easily monitor the RPM of the external fans. If one of them drops to near zero, which would happen for example if the adapter breaks, then i want to give the controlling proces there the order to cut the power of the switch.

Writing the software i'll manage, but what device to use that i can control by software or maybe even a simpler solution is there.

Note that i do realize this is not a 100% solution, yet the odds that one day the 12 volt adapter breaks is there, so i want to catch THAT possibility.

I feel some cheapskate solution probably exists. Any thoughts on how to solve this i welcome.
This linux, windows, or some other custom o/s???

In linux it is pretty easy to write a shell script to access the lm_sensors info, and if a fan's rpm drops to some chosen value, shut the system down quickly...
Right lm_sensors it is. Problem is not the software. Problem is how to interrupt power of the switch. I need a device that can react onto the computer.

Now i can of course buy a legorobot that can do it using robot-OS - maybe there is something cheaper.

The switch doesn't have a 'turn off' button.

So i need to physical build something that can be steered by computer. Any thoughts on that?

jwes
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Re: Cutting power by software - what device do i need?

Post by jwes » Mon Mar 19, 2012 6:19 pm

google usb relay.

diep
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Re: Cutting power by software - what device do i need?

Post by diep » Mon Mar 19, 2012 8:05 pm

jwes wrote:google usb relay.
Ah yes i see i can plug relays into the computer. That's good.
It can give a pulse. That's a good start :)

Any idea how to switch off power with such pulse? Probably need another device that i plug into the relay then?

bhlangonijr
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Re: Cutting power by software - what device do i need?

Post by bhlangonijr » Mon Mar 19, 2012 8:54 pm

diep wrote: Right lm_sensors it is. Problem is not the software. Problem is how to interrupt power of the switch. I need a device that can react onto the computer.

Now i can of course buy a legorobot that can do it using robot-OS - maybe there is something cheaper.

The switch doesn't have a 'turn off' button.

So i need to physical build something that can be steered by computer. Any thoughts on that?
... and what happens if you try issuing a "shutdown -h now" ?

diep
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Re: Cutting power by software - what device do i need?

Post by diep » Mon Mar 19, 2012 9:27 pm

bhlangonijr wrote:
diep wrote: Right lm_sensors it is. Problem is not the software. Problem is how to interrupt power of the switch. I need a device that can react onto the computer.

Now i can of course buy a legorobot that can do it using robot-OS - maybe there is something cheaper.

The switch doesn't have a 'turn off' button.

So i need to physical build something that can be steered by computer. Any thoughts on that?
... and what happens if you try issuing a "shutdown -h now" ?
That's not a problem as i'm there then. The real problem is when i'm asleep that the cheapo 12 volts adapter that runs fans of a precious Mellanox component, that it breaks.

The component will overheat and die then.

Sure there is possibilities like a power failure, and that it'll take a while for the machine to reboot, meanwhile the adapter by accident broke (it can survive power failures and shockwaves of 330 volt that adapter - already tested that) and that booting the linux box takes so long that the Mellanox switch already fried itself, but that's another issue.

The scenario i want to avoid is a much simpler one and that's that the adapter breaks when i'm asleep and that a cheap trick of me to reduce a 70+ decibel component using a cheapo old adapter, that this adapter breaks, which is a thing that happens more, and that it melts the switch :)

Not sure Mellanox happy with me asking for another switch :)

Vincent

syzygy
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Re: Cutting power by software - what device do i need?

Post by syzygy » Mon Mar 19, 2012 10:27 pm

diep wrote:
bhlangonijr wrote: ... and what happens if you try issuing a "shutdown -h now" ?
That's not a problem as i'm there then. The real problem is when i'm asleep that the cheapo 12 volts adapter that runs fans of a precious Mellanox component, that it breaks.
I think the question is what happens if you let a script issue the "shutdown -h now" when the temperature gets too high?

diep
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Re: Cutting power by software - what device do i need?

Post by diep » Mon Mar 19, 2012 11:15 pm

syzygy wrote:
diep wrote:
bhlangonijr wrote: ... and what happens if you try issuing a "shutdown -h now" ?
That's not a problem as i'm there then. The real problem is when i'm asleep that the cheapo 12 volts adapter that runs fans of a precious Mellanox component, that it breaks.
I think the question is what happens if you let a script issue the "shutdown -h now" when the temperature gets too high?
Then the computer will shut down but not the switch. The switch has no button to turn off.

So the switch will melt, as i removed the internal fans from switch as those make 70+ decibel. An external computer i can have monitor those external fans and undertake action when it notices that they stop working or one of them.

So one solution is to have a legorobot equipped with a small hammer and have it hammer on a button, having the computer steer the legorobot, and turning off the switches power by hammering onto the button of the 240 volt power with the lego robot.

Big odds that hammering goes wrong.

bob
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Re: Cutting power by software - what device do i need?

Post by bob » Mon Mar 19, 2012 11:27 pm

diep wrote:
bob wrote:
diep wrote:hi,

My chessprogram runs on a box that uses a switch that doesn't have a 'power off' button.

This mellanox switch however, you can see from my facebook pictures there (my entire facebook is open to the entire world to browse), it produces 75 decibel or so and i sit a few meters away from it.

Now i got rid of the fans from the switch and replaced it by cardboard and big outside fans. Where the psu can give power to 1 fan that cools the psu (hopefully it'll go ok as the airpressure of the fans i use isn't that high), the other 3 fans from the case do not have this luxury solution. The easiest solution is use an external adapter.

This external adapter could break at which point a disaster might happen to the switch. From 1 of the motherboards of the box i can easily monitor the RPM of the external fans. If one of them drops to near zero, which would happen for example if the adapter breaks, then i want to give the controlling proces there the order to cut the power of the switch.

Writing the software i'll manage, but what device to use that i can control by software or maybe even a simpler solution is there.

Note that i do realize this is not a 100% solution, yet the odds that one day the 12 volt adapter breaks is there, so i want to catch THAT possibility.

I feel some cheapskate solution probably exists. Any thoughts on how to solve this i welcome.
This linux, windows, or some other custom o/s???

In linux it is pretty easy to write a shell script to access the lm_sensors info, and if a fan's rpm drops to some chosen value, shut the system down quickly...
Right lm_sensors it is. Problem is not the software. Problem is how to interrupt power of the switch. I need a device that can react onto the computer.

Now i can of course buy a legorobot that can do it using robot-OS - maybe there is something cheaper.

The switch doesn't have a 'turn off' button.

So i need to physical build something that can be steered by computer. Any thoughts on that?
OK, the switch is a separate box, completely. And you want to be able to turn it off from the computer?

If I were going to try to build such a thing, I might "go simple here." Take one pin + ground from the parallel output port, and gate that to a simple darlington-pair power transistor that is used to ramp up the current to a level that will trip a relay. Then simply wire the spdt relay in series with the hot wire on the a/c power, and you are set. Output a 1, the relay closes, and power comes on. Output a 0, the relay opens, power goes away.

If you want it to "default on" you could toss in a "not" gate on the signal coming from the parallel port output, as it almost certainly powers on with an output of all zero bits. Notting that would give you a 1 which would start things off with the switch power enabled...

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