5 volt 4-wire PWM fan wiring

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mjo2125
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5 volt 4-wire PWM fan wiring

Post by mjo2125 » Fri Mar 23, 2018 2:24 pm

With 5v BCS 460 output, do i need a power supply for the computer 5 v fan to operate in PWM, or can the fan be directly connected to the BCS 460 (bcs 460 powers the fan)?

I'm hacking a fridge for fermentation (heating and cooling)

thanks.

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JonW
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Re: 5 volt 4-wire PWM fan wiring

Post by JonW » Fri Mar 23, 2018 11:20 pm

Always use a relay to switch the power to your device. The BCS 460/462 outputs are NOT designed to power devices, only trigger them (via relay).

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Re: 5 volt 4-wire PWM fan wiring

Post by mjo2125 » Fri Mar 30, 2018 8:11 am

thanks - I'm also thinking of using a NOYITO DC 12 v, 2A fan power adapter to power the fan rather than an SSR.

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Re: 5 volt 4-wire PWM fan wiring

Post by mjo2125 » Mon Dec 31, 2018 9:04 am

I have a +12 V DC power supply for the fan. I understand the BCS will send a +5V DC PWM control signal to the fan when the fan output is asserted. Question: When no fan output is specified for a process, will the fan go to 0% or will the fan continue to run at 100% on +12 V DC power? Do I need a DC/DC SSR between the fan power supply and the fan to insure the fan is not running when no output is asserted to it?

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JonW
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Re: 5 volt 4-wire PWM fan wiring

Post by JonW » Mon Dec 31, 2018 12:16 pm

You've mentioned PWM in your first post and again here. Are you trying to do a variable speed controlled fan? I'm thinking you really just want (and mean) on/off control, not PWM. Real PWM is really only useful for heating elements. No need to do PWM for a fan in a fermenter, just on/off control is what you want.

If you are not asserting the output to trigger your 12V relay, then your fan will be off. Outputs can be turned on manually from the main interface screen, by process control or by ladder logic control. If the output is not turned on by one of those 3 options, then it will remain off.

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Re: 5 volt 4-wire PWM fan wiring

Post by mjo2125 » Mon Dec 31, 2018 12:38 pm

Hi Jon, I'm looking at on/off control for a percentage of time during a process step - similar to what is done in computer CPUs with PWM fans. I'd rather avoid having the fan on 100% of the time during a process step.

Ideally, I'd like to do a variable speed control but I don't think it's possible to program that for automatic control with the BCS. So I'm trying to meet in the middle with PWM as a compromise between variable speed and 100% all the time in a process step.

thanks

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oakbarn
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Re: 5 volt 4-wire PWM fan wiring

Post by oakbarn » Mon Dec 31, 2018 5:00 pm

Look at Duty Cycle control if you want it on for a time then off

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Re: 5 volt 4-wire PWM fan wiring

Post by mjo2125 » Tue Jan 01, 2019 6:52 am

ok. The fan is a 4-pin device - (ground, +12 VDC, Tach, and PWM signal). It will get power from a 12 vDC power source (the first two pins will be used)and the BCS signal will be connected to the PWM pin to control the fans using a Duty Cycle control. I tried to simulate an open BCS signal (open ended wire) to the PWM pin assuming the fan would not run w/o a signal. But the fan ran at 100% with the open ended signal wire - (I expected the fan not to run with an open control circuit). I will actually hook it up to an assigned BCS output terminal (non-asserted) to see if the fan stops running. If it doesn't, I'll need to place a DC/DC SSR between the power source and fan to insure it doesn't run when the output isn't asserted.

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Re: 5 volt 4-wire PWM fan wiring

Post by oakbarn » Sat Jan 05, 2019 4:49 pm

I would not do it that way. I would hook up 12 Vdc gnd to the fan gnd. I would put in a SSR with the 12 vdc + on the load side and the other load to the fan 12 vdc +. The bcs Out to the control of the ssr and the bcs gnd to the ssr gnd

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Re: 5 volt 4-wire PWM fan wiring

Post by mjo2125 » Sat Feb 02, 2019 6:12 pm

Decided not to use the BCS for fan control. I'll use a variable speed power supply to control the fans. The fan tach output will be sent to an Arduino and RPM monitored via a 16x2 LCD display.

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