# Specific 3D Printers, Scanners, & Hardware > Other 3D Printers / Scanners / Hardware > Printrbot Forum >  Assigning static com ports to printers

## royeven

Hi

I have six Printrbot Simple Metal (work with education). They are connected to a usb hub which is connected to my PC. I use cura as my printing program. I would like to assign a static com port to each printer so I can easily choose which printer to use. My problem now is that printers change com ports all the time. A printer that was on COM3 last time I used it can be on COM9 the next day. I do not move the cables around, each printer has a fixed port in the hub, it's the OS that keeps changing port numbers. According to [1] and [2], USB devices tend to receive the same COM number every time it is connected to the computer according to their VID, PID and Serial Number. However, is it possible that all my printrbot simple metal has the same VID, PID and Serial Number? Is it possible to change this behaviour so that I can differentiate between the printers?

[1] http://stackoverflow.com/questions/1...-in-windows-xp
[2] http://www.ftdichip.com/Support/Docu...stallation.pdf

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