Black Box Express 8-Port Mux User Manual page 18

A device is down or unstable.
· Verify that there is one host polling group per Express 8-Port Mux polling group.
· Verify that the host's device type matches the device.
· Verify that the host workstation controller's capacity has not been exceeded.
· Verify that the device is properly terminated. A peripheral is terminated when its twinaxial port has two
54.9-ohm resistors located between the "A" phase pin & earth ground and the "B" phase pin & earth
ground. Termination is provided by a "Y" or "T" cable assembly or by a terminating balun (that is, ASFT
series).
· Verify that there are no polarity reversals in the cable.
· Verify that the cable distance does not exceed the Express 8-Port Mux specification.
· Verify that the cable is data grade.
· Verify that the wiring uses natural pairs.
· Verify that the wiring avoids sources of environmental noise.
· Verify that the balun's pinout matches the Express 8-Port Mux's pinout.
· Verify that the host side balun's pinout/polarity match the device side balun's pinout/polarity.
Devices interfere with each other.
· Verify that there is one host-polling group per Express 8-Port Mux polling group.
· Verify that devices on star segments have unique addresses.
· Verify that all devices are properly terminated.
Devices cannot operate in Express mode.
· Verify that the host and the device are capable of Express mode.
· Verify that all interconnecting components support the Express mode.
· Verify that all devices on the port are Express ready.
· Verify that all cable distances are within the Express specification.
· The controller may have downshifted to 1 Mbps because of errors during installation. The controller will
retry the Express mode in approximately one hour.
Flashing Express LEDs.
· Determine the number of Express devices on the port. If there are less than seven devices, the flashing
Express LED is normal.
Express LED on without data activity.
· If the host is disconnected during an express connection, the express LED remains on.
EXPRESS 8-PORT MUX
17