Secondary Connector (Rows C And D); Pci Express - Kontron ETXexpress-WPM User Manual

7. Secondary Connector
(Rows C and D)
The secondary connector (Rows C and D) provides support for the following buses and
I/O:
•

PCI Express

• PCI Bus
• Ethernet Port – 2x GbE
• Serial Port (x1)
PCI Express
PCI Express is an I/O interconnect bus standard (which includes a protocol and a
layered architecture) that expands on and doubles the data transfer rates of the original
PCI specification. PCI Express is a two-way, serial connection that carries data in
packets along two pairs of point-to-point data lanes, compared to the single parallel data
bus of traditional PCI that routes data at a set rate.
Initial bit rates for PCI Express reach 2.5Gb per second per lane direction, which equate
to data transfer rates of approximately 200MB per second. PCI Express was developed
so that high-speed interconnects such as Firewire (1394b), USB 2.0, InfiniBand, and
Gigabit Ethernet would have an I/O architecture suitable for high-speed transfers.
The ETXexpress-WPM supports up to 12 PCI Express lanes across its two connectors.
Their availability varies somewhat depending on whether the dual Gigabit Ethernet
option (see below) is utilized. Regardless of that option, 8 PCI Express lanes are
available as Port A and are split into 2 x4 ports (an upper port and a lower port, i.e. Port
A [0-3] and Port A [4-7]).
If the dual GbE chips are installed, then only 2 out of the 4 Port B PCI Express lanes are
available on the baseboard and are configured in x1 mode only. (The remaining two
lanes are used by the Gigabit Ethernet, of course.) These two lanes are PCIE[0-1] on
the COM Express connector. If the dual GbE chips are not installed, then all of the Port
B PCIE lanes are available on the baseboard and may be configured as either 1 x4 port
or 4 x1 ports.
Configuration
The BIOS automatically configures settings for the PCI Express bus. However, you can
configure support for the PCI bus from the BIOS Setup Utility. (Press the Delete button
during reboot to see the BIOS Setup Utility.)
ETXexpress-WPM User's Guide page 39