Canon VC-C3 User Manual page 9

3) If you have the COM port configured but it is being used by another
device such as a modem, this error will be displayed:
4) If the VC-C3 is not connected to the selected configured COM
port, this error will be displayed:
Note: There may be a several second delay before an error message
shows, depending on how far the initialization gets before an error is
encountered.
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