View source for Force same COM port assignment to all D.Module2.C6657

== Problem ==
When a new D.Module2.C6657 is connected via USB to your PC, a new free COM port is automatically assigned by the installation wizard. If this default behavior is not suitable because an application needs to be controlled always by a fixed port, a user could follow [[Re-assign_virtual_COM_port|Re-assign virtual COM port]] to manually change the COM port for a specific device or use the instructions below to permanently change this behavior for all D.Module2.C6657. 

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== Solution ==
The automatic new COM port assignment is caused by a unique serial number programmed into the FTDI chips on all D.Module2.C6657 boards. With a specific registry switch all D.Module2.C6657 FTDI serial numbers can be excluded from the default automatic COM port assignment. Create a '''''REG_BINARY''''' value '''''IgnoreHWSerNum04036015''''' set to '''''01''''' under

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags 

or use the following .reg script to add the key to your registry:

<syntaxhighlight lang="c">
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\usbflags]
"IgnoreHWSerNum04036015"=hex:01
</syntaxhighlight>

{{note|It might be necessary to follow [[Re-assign_virtual_COM_port|Re-assign virtual COM port]] to initially assign a specific port}}

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== Additional Tags ==
http://www.ftdichip.com/Support/Documents/AppNotes/AN_123_How%20COM%20Ports_Are%20Allocated%20on%20Driver_Installation.pdf



 [[category:D.Module2.C6657]]