User Manual

PremierWave EN User Guide 31
5: Line and Tunnel Settings
The PremierWave EN contains three Lines. Lines 1 and 2 are standard RS232/RS485 serial
ports, while Line 3 is an emulated serial port over the USB Device (USB-CDC-ACM).
RS232/RS485
Lines 1 and 2 can be configured to operate in the following modes:
 RS232
 RS485 Full Duplex
 RS485 Half Duplex, with and without termination impedance
 All serial settings such as Baud Rate, Parity, Data Bits, etc, apply to these Lines.
USB-CDC-ACM
Line 3 can only operate as an emulated serial port over the USB Device port. It uses the
standard CDC-ACM protocol, which is supported natively by most host operating systems
(Windows, Linux, etc.). Since it is an emulated serial port, most standard serial port settings
are irrelevant. Flow control is inherent to the USB protocol, and the line speed (Baud Rate)
will be “as fast as conditions permit”.
When the PremierWave EN USB Device port is cabled to a host, it will identify itself with the
industry standard USB Vendor ID of 0x0525 and Product ID of 0xa4a7.
When attached to a Windows host, a device driver .inf file (see Appendix E - USB-CDC-ACM
Device Driver File for Windows Hosts) must be installed the first time the port is cabled.
Once installed, Windows will configure an available COM port, each time the USB cable is
attached.
CAUTION:
When attached to a Linux host, the USB-CDC-ACM connection will automatically be
configured, assuming the Linux host is configured for USB host operation and the “cdc_acm”
driver is available. Once recognized, the cdc_acm driver will configure a standard serial port
in the /dev/ttyACMx series, where x is a number 0, 1, 2, 3, etc.
Under Windows, if the PremierWave EN device is rebooted when an active
COM port is configured and in use, the COM port will come back up in an unstable
state. When this happens, any terminal program accessing the COM port must be
disconnected, and the USB cable physically replugged (or the COM port under Device
Manager disabled/enabled).
CAUTION:
Under Linux, if the /dev/ttyACMx device is in use when the PremierWave EN
is rebooted, some terminal programs under Linux will automatically disconnect while
others will not. If a terminal program does not disconnect automatically, when the
PremierWave EN comes back up, the CDC-ACM connection will be enumerated to a
different /dev/ttyACMx device.