User`s manual

The diagnostics program also tests the ability of the card to generate interrupts by way of internal data loopbacks. It
tests all found ports. For example, a 4 port board will prompt you to move the loopback connector when performing the
external data and control signal tests.
The internal and external tests are run at the maximum supported bit rates for their respective interfaces. On the
internal tests, all available channels are run simultaneously at the maximum bit rate to help resolve arbitration and memory
bandwidth issues.