umcs(4) USB support for serial adapters based on the MCS7820 and MCS7840 chips


To compile this driver into the kernel, place the following lines in your kernel configuration file:
device usb device ucom device umcs

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf5:



The driver provides support for various multiport serial adapters based on the MosCom MCS7820 and MCS7840 chips. They are 2- or 4-port adapters with full-featured 16550-compatible UARTs and very flexible baud generators. Also, these chips support RS422/RS485 and IrDA operations.

The device is accessed through the ucom(4) driver which makes it behave like a tty(4).

Different ports on device are presented as sub-units, like /dev/ttyU0.1 and /dev/ttyU0.2


The driver was tested on the following adapters:

  • ST Lab U-360 two-port serial USB adapter
  • ST Lab U-400 four-port serial USB adapter


The driver appeared in ports since December of 2010.


An -nosplit The driver was written by An Lev Serebryakov Aq [email protected] .


This driver doesn't support access to any fine tunes of chip, like RS522/RS485 mode, non-standard baudrates, etc.