Distributor of VersaLogic Corporation: Excellent Integrated System Limited
Datasheet of VL-CBR-2012 - 20" 24-BIT LVDS CABLE
Contact us: [email protected] Website: www.integrated-circuit.com
Interfaces and Connectors
VL-EPMs-21 Reference Manual
36
Serial Ports
The VL-EPMs-21 features four on-board 16550-based serial channels located at standard PC I/O
addresses. Connector J7 provides interfaces to the COM ports.
All COM ports can be operated in RS-232, RS-422, or RS-485 modes. The default mode is RS-
232.
Note:
To operate a serial port in RS-232 mode, the termination jumper for the port must
be removed from jumper block V1 (see Jumper Summary). Failure to remove the
jumper will cause RS-232 communications to fail.
Additional non-standard baud rates are also available (programmable in the normal baud
registers) of up to 460 Kbps. The RS-232 interface is 4-wire with CTS and RTS hardware
handshaking.
Interrupt assignment for each COM port is handled in CMOS Setup, and each port can be
independently enabled or disabled.
Note:
It is possible to create a resource conflict if a COM port is enabled in CMOS and
its I/O address space is consumed by an LPC-based SUMIT module or forwarded
to the PC/104 (ISA) bus.
Note:
You can improve the reliability of serial port traffic running at 11520 bps or greater
by disabling the Periodic SMI option in CMOS Setup. (See KnowledgeBase article
VT1628 - EPMs-21 CMOS Setup Reference
for more information.) Enabling this
option gives periodic CPU time slices to Firmbase after POST completes. Firmbase
primarily allows USB keyboards and mass storage devices to behave as legacy
PS/2 and IDE devices for operating systems such as DOS, which don't natively
support USB.
All serial ports are protected against ESD damage. This protection exceeds the 15KV human
body model.
COM
P
ORT
C
ONFIGURATION
Jumper block V1 controls termination of the RS-422/485 differential pairs. See the Jumper
Summary on page 19 for details on termination configuration.
Note:
To operate a serial port in RS-232 mode, the termination jumper for the port must
be removed from jumper block V1 (see Jumper Summary). Failure to remove the
jumper will cause RS-232 communications to fail.
43 / 64
43 / 64
