StepperBoard COM Port Naming Rules

Windows has a rather strange syntax for defining com port names for ports above 9 (i.e., ports 10 through 255) -- it requires use of the network predicate string "\\.\" to be prepended to the COM port name.  For example, Com port number 10 would appear as:


All versions of our StepperBoard class library compiled before March 24, 2007 do NOT use this convention when an automatic scan for a com port is performed.  This means that they will not successfully open  any port above port 9, unless your code manually generates the correctly formed port name.  All versions from March 24 on will automatically generate the correct port name by prepending the network predicate string to any port name which does not have a "\" already present as the first character of the port name.

Note that this means that our standard "ScanSerialPorts" application must also be dated March 24, 2007 or later in order to correctly handle COM ports above port number 9.

Similarly, if you use our "SerTest" application and your COM port is above port 9, you will have to use the same syntax on your command line invocation to specify the port:

    SerTest /p\\.\COM10 ...your commands to send to port COM10 go here