DVMR Link Status Diagnostic

Diagnostics > System Function > Acquisition/Pulse Generation

Diagnostics > Hardware Location > Acquisition/Pulse Generation

Figure 1. DVMR Link Status Diagnostic

The DVMR Link Status Diagnostic accesses the SFP (small form-factor pluggable) fiber optic transceivers connecting the MGD or CAM chassis to external modules. It tests the SFP fiber optic transceivers used by many components in the MR system and reports the health of the SFP with a status of PASS or FAIL. A PASS result indicates all SFPs working per design and no action required. A FAIL result with an action statement such as “'Replace the SFP” requires the FE to perform the recommended action.

This diagnostic does not report data for SFPs on the VRF boards in the ICNs or the SFPs on the legacy XGA and XPS gradient hardware in the XGD subsystem, which includes a Cronus Chassis.

• SFP fiber optic transceivers in all devices, except VRF and XGD

• All corresponding dual-fiber optic cables

caution Potential Component Damage! Electrostatic discharge (ESD) can cause permanent damage to electronic components. Observe the following ESD precautions: Work on a static-free mat. Wear a static strap to ensure that any accumulated electrostatic charge is discharged from your body to the ground. reate a common ground for the equipment being worked on by connecting the static-free mat, static strap, and peripheral units to that piece of equipment.

caution Potential Component Damage! The SFP optical transceiver is very sensitive to electrostatic discharge, dust, and body oil. When working with the SFP optical transceiver: Always use ESD protection when handling the SFP optical transceiver to prevent early failure. Never touch the SFP optical transceiver without being properly grounded. Never touch the end face of the optical connectors. Never reuse lens tissue or cleaning swabs. Always keep a protective cap on unplugged fiber connections. Always inspect the connection before cleaning. The SFP must be shipped in antistatic packaging. Discard any SFP shipped or stored without proper ESD protection. Some SFPs are shipped in insulated envelopes which can produce excessive contaminates. Do not open these containers in the area where you will be working with the SFP. Remove the antistatic bag containing the SFP and move to a clean area to work.

Most SFP failures are due to ESD events. ESD events as low as 400 V are known to damage SFP modules. ESD events are commonly 5 kV or more.

Other failures are due to SFP optics and exposed glass Rx and Tx ends of cables being fouled by contaminants. Do not touch the exposed ends on fiber connectors. Leave the dust caps in place until you are ready to install the SFP module. For more information on handling and cleaning the SFP transceiver, see Fiber Optic Cable Devices Installation and Replacement.

Figure 2. SFP Fiber Optic Transceiver

SFPs must be connected through dual-fiber (Tx, Rx) cable to SFP in another device.

1. Navigate to DVMR Link Status Diagnostic (see Figure 1).

2. Click Run.

Diagnostic results display the device and connection with a status of PASS or FAIL.

In the following example, the diagnostics reports the IXG J12 with a status of PASS. Additional information is also reported: voltage, temperature, transmission bias, transmission power, receiving power, whether a signal has been detected, and name of the component where the signal ends.

Figure 3. DVMR Link Status Diagnostic PASS Result

In the example below, the diagnostic reports FAIL with no signal detected, a phantom Rx power signal, and no prescribed action. If a remote device is plugged into J12, there is not enough signal. If J12 is unused, there is too much rxPwr being reported. It is a phantom signal; rxPwr should be 0. In both cases, the recommendation is to replace the SFP.

Figure 4. DVMR Diagnostics Reports FAIL and No Signal

caution Potential Component Damage! Dust and oil from your hand can contaminate the end of the LC connector on the fiber optic cable and the SFP. Avoid touching the end of the LC connector and the SFP. If you must leave the cable unconnected for any period of time, cover the end of the LC connector with a protective cap. Also cover the end of the SFP with the protective cap.

If the diagnostic reported a signal detected on the port and low rxPwr, there are several things to check to find out why the rxPwr is low:

• Verify that both ends of the fiber are securely seated.

• Clean the fiber optic ferrules on both ends of the cable, and clean the connection points on the SFP on both ends. See Fiber Optic Cable Devices Installation and Replacement. Then retest.

• Try using a spare fiber and retest.

• Replace the SFP on the far end of the fiber and retest.

• Replace the SFP on the local end of the fiber and retest.

If the signal is still weak, replace the SFP. If the signal is still weak after the replacing the SFP, replace the cable.

In the example below, the diagnostic reports FAIL with no signal detected and prompts you to replace the SFP on J13.

The diagnostic determined that this SFP is defective and must be replaced.

Figure 5. DVMR Link Status Diagnostics Reports FAIL