Can you stop Windows polling the serial ports on boot up?

[Chris Wilson]

I have some devices (solid state relays controlling large mains power supplies) running off the true serial ports on my motherboard. I use this set up to remotely switch the supplies on or off via remote desktop using a simple DOS program. However, on boot up Windows 7 64 bit seems to "poll" the ports sending outputs momentarily high a few times. The SSD's, the big linear power supplies and I don't like this! Can it be stopped? Thanks.

 

[Chris Wilson]

Have a look at https://superuser.com/q/631532/635122

That looks just the ticket, many thanks from me, my SSD's and my PSU's

 

[Chris Wilson]

Could also try turning off Serial Enumeration in advanced properties from Device Manager?

Is that under Device manager - Ports? If so that option doesn't seem available here... Thanks anyway.

 

[Chris Wilson]

From my limited knowledge I think you are going to need a more advanced solution - either some kind of blip logic/power on detection circuitry or swapping to something like an Arduino Nano to control the relays.

Or move the system to another low power always on device.

I can't try the aforementioned method until tonight, I'll report back, hopefully it will work, the info certainly suggests it can do the trick, time will tell, thanks.

 

[Chris Wilson]

Unfortunately this has not worked. Someone elsewhere said it may be hard coded in the BIOS, but the sigs to the Serial Port do not occur until after the Starting Windows logo and just as the password prompt screen shows. it goes through two phases of polling the serial port about 5 seconds apart. I did the bcdedit /enum and after several reboots the off setting had stuck every time. I have also turned off the serial mouse in the registry with no effect. Thanks for the suggestion, any other ideas for me to try please?

 

[Chris Wilson]

Thanks, I also tried killing search for a serial mouse, as per the above, but that too had no effect, but thanks for the idea BattFink

 

[Chris Wilson]

So does your receiving device simply change states based on a high signal coming into it from the serial port, or is it specific commands send down the line?

I would agree with the comments that your system reads as though it needs a bit more resilience to random inputs.

Yes, the DOS app just allows manual on or off, simple commands as far as my (very limited) knowledge allows. the ONLY issue I ever see is upon boot up, after the Windows log on screen.

 

[Chris Wilson]

I haven't tried booting in to Safe Mode, but I will. To be frank I saw my backside with it and made a little 5V linaer power supply in an alloy and now use an RF switched 13 amp plug socket adaptor to power the 5V supply and in turn that switches the big solid state relay. i can't operate it away from home, but at least it doens'y have a mind of its own i will try Safe Mode though, but further reading shows many others have this (including Mr Feek), and it was impossible to tame. Thanks for the replies everyone!

 

[Chris Wilson]

Definitely worth looking into something with a microprocessor like the Arduino (the Nano has a fairly simple interface and lots of output options) or RPi for this kind of thing.

I am probably too old to bother getting in to programming stuff, but I certainly agree they are extremely useful gizmos! Thanks.

 

[Chris Wilson]

I'd posted previously on fake chinese SSR's catching fire ... so hope you got a bona-fide one.

It's in a sealed alloy box on a hefty heat sink, so whatever it does will be safely contained, but thanks for the warning! I had one fail and as you say, care needs to be taken. marked as a 40 amp SSR it actually had a 16 Amp Triac in it....