Serial mode selection

At any given time, only one serial mode can be selected. The XLR PRO selects the serial mode based on cable connections detection and configuration options.

USB
XLR PRO detects DTR on the USB virtual COM port.
RS-232
XLR PRO detects DTR on the RS-232 serial port.
RS-485/422
RS-485 configuration option is enabled or disabled via the 4E (Enable RS-485 Mode) parameter.
IP socket
IP Socket configuration option is enabled or disabled via the ES (Enable IP Socket Mode) parameter.

The following flow chart depicts how the XLR PRO selects serial mode:

There must be an active DTR signal to automatically detect an RS-232 serial connection. If the serial cable or end device does not include an active DTR signal, disable IP socket mode (ES = 0) using XCTU, the web configuration, or Device Cloud.

By default, RS-485 mode is disabled (4E = 0) and IP socket mode is enabled (ES = 1). So, by default, RS-232 mode is selected if DTR is present. Otherwise, IP socket mode is selected. Use the 4E and ES configuration parameters to select other modes, independent of DTR, which may not be present on a serial port connection.