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Com ports keep changing numbers


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Hello,

 

I have a brand new HP desktop running Win 8.1 Pro and have two LOR USB-485 adapters (with Voltage Booster) connected to two USB ports.  I am running two LOR networks.  I do not unplug these LOR adapters from my computer.

 

Often, they change com ports whenever I restart or turn on my computer.  Sometimes they'll be Com 3 and Com 4, sometimes they'll be Com 1 and Com 2.

 

I tried going into Device Manager and forcing the adapters to be Com 1 and Com 2, but somehow, they changed back to Com 4 and Com 3.

 

Please help.  I attached some screenshots of my Com port settings.

 

Stan

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post-3253-0-28281600-1417071162_thumb.jp

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This question intrigues me...you might first want to get a help desk ticket started with LOR as they've probably already seen this. However, I did a little digging and so far, only found one area of interest. The advanced power settings in the control panelpower area. Apparently 8.1 has the ability to save power by turning off USB ports when not in-use, therefore the reassignments of serial communication takes place. Now truly this is just something you can try...no promises.

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Are you plugging in or unplugging other USB devices prior to booting up. Say you left in a memory stick and booted up one time. But removed it and was not present when booted again. Or a ext. Hard drive with USB interface? Though no experience with this that dgrant mentions. Sounds like it might have merit. I would turn off any power management of USB ports (always on).

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I think you should try higher numbers.   Above 4.   The lower ones may have legit legacy functions. 

 

The adapter has an internal serial number which is associated with a com port.  It CANT change on its own.   On a different PC that adapter will get a different port number.  The switching you see is from competition from another process. 

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I am not plugging in/removing any USB hardware upon bootup, or shutdown, etc.

 

 

And Bob, I will try higher numbers than Com 1-4.

 

 

Another question, why is the com port defaulted to 9,600bps?  I thought LOR likes 57.6kbps?

 

thank you all,

 

Stan

Edited by stanward
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  • 1 month later...

Opened a trouble ticket back in late November with no luck.  Person from LOR said to use Google to find my answer.

 

For the majority of December, my two adapters used Com 5 and Com 6.  I shut the computer off after each show.  Com port 5 all of a sudden became Com port 7 (towards the end of December).  My computer likes to play "musical" com ports!!!!

 

I can't find anything on Google.

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Another question, why is the com port defaulted to 9,600bps?  I thought LOR likes 57.6kbps?

 

thank you all,

 

Stan

 

You can ignore that.  That is an ancient legacy.   The program that uses the serial connection uses whatever speed it is set for.  I have not seen a program in 25 years that paid any attention to that.

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