White Paper: PCI Express(r) Over Cable Link Tuning Essentials

PCI Express(r) Over Cable Link Tuning Essentials

PCI Express (PCIe) has evolved very quickly from a component interconnect on a PC board into the pervasive system I/O interconnect of choice in a wide variety of industrial computers and servers.

So does a customer need to purchase an expensive PCI Express protocol analyzer and fiddle around with device parameters like pre-emphasis and equalization to get a good PCIe signal sent over a copper cable to an I/O expansion chassis? Not at all! These parameters are engineered into the PCIe components used in the target and host boards and optimized for a variety of application scenarios.

There may be diagnostic LEDs and dip-switches incorporated into the PCIe host and target expansion card to enable a user to make field adjustments as necessary to decrease the rate of data re-tries, but these adjustments will only be required in extreme applications such as using maximum cable lengths with high-speed PCI Express 3.0 applications. In general the default settings of the dip switches should meet most system requirements. It’s unlikely that these dip-switch adjustments will be needed with the majority of PCI Express over cable installations, but it’s nice to know that they are there if needed.

PCI Express expansion chassis can be implemented quickly and effectively to expand the I/O card capabilities of an existing host server with proper understanding of the underlying engineering principles of PCI Express over cable. An I/O expansion system using PCIe over cable will extend the capabilities of an existing host server at a significant cost savings compared to installing all new host and I/O hardware and software