> 2.8.2 | Power Down after Closing the Last Port

> When the last virtual port is closed the module switches from multiplexer mode to “normal AT command mode”. This is accomplished by sending the strings of the Registry value “ClosePort” to the module (AT+IPR=0 and, depending on the product, AT^SMSO).
> If the module is switched off with AT^SMSO, the driver waits for the DSR signal to go low after switch-off. Otherwise reopening a virtual port may fail because the module hasn’t finished its shutdown procedure. This behavior is supported by Multiplexer Protocol version 3 or later and enabled by the Registry value “WaitForDSR” = 1.
> Due to different requirements of the supported products the Registry values “ClosePort” and “WaitForDSR” vary with the module type. By default, all modules except for TC45 and XC18 will be switched to autobauding with IPR=0 and then turned off by AT^SMSO, with the “WaitForDSR” feature being enabled. TC45 and XC18, however, will only be set to autobauding and not switched off, and therefore the “WaitForDSR” feature is disabled. As stated in Section 2.3, this default behavior of TC45 and XC18 was implemented for faster access from the PC debug environment.