Background

Unit	IP	Location
deits2	192.168.6.2	Bay D of DEIMOS cradle (bay to the left of roto)
deits3	192.168.6.4	Bay 3 of DEIMOS barrel

The first indication of a problem with the Lantronix terminal server on DEIMOS might be problems commanding motors. Other symptoms may exist as well but this problem can be confirmed by running testAll on polo. If the Lantronix unit is unresponsive, the return from this command will indicate a problem communicating to the Lantronix. The first thing to try is the soft reset procedure, which can be done remotely. If this should fail, the following more serious procedure may be used to power cycle the Lantronix unit.

Procedure for Cradle Lantronix

1. Remove Bay D cover. To access the Lantronix power switch, remove the Bay D cover by undoing the red thumbscrews and lifting the cover off.
2. Locate Lantronix. The terminal server should be located between the blue AC outlets and the Netgear hub as shown in this photo.
3. Cycle power. Use the rocker switch on the front (top) of the Lantronix unit to turn power off. Wait a few seconds, then turn power back on. Figure 3 shows the Lantronix terminal server and the rocker power switch.
4. Verify communications. Execute the DEIMOS testAll script to confirm that the DEIMOS host computers are able to communicate with the Lantronix unit. If so, then proceed with re-installing the rear cover. If not, check cabling as described next.
5. Check cabling. Inspect the cabling at the back of the Lantronix, including the coax cable and adapter. Confirm that all cables are securely plugged in. If none are suspect, you might try unplugging individual cables and plugging them back in. In particular, confirm that the AUI (10Base-2) adapter is firmly plugged into the port on back of the Lantronix.
6. Re-verify communications. Execute the DEIMOS testAll script again to confirm that the DEIMOS host computers are able to communicate with the Lantronix unit. If so, then re-install the cover. If not, try another power cycle. If this fails to fix the problem, then the Instrument Technician should configure and install a spare Lantronix. Night staff should not attempt this repair.

Procedure for Barrel Lantronix

1. Rotate DEIMOS. Rotate DEIMOS to access electronics bay 3. The electronics bays are located around the large ring-like structure at the back of the instrument. They are labeled with numbers and contents. There are three ways to set the instrument rotator position:
   • Have the observer rotate DEIMOS to an angle of 0° or 180° from the DEIMOS rotator GUI.
   • Have the OA rotate DEIMOS to physical drive angle 90° or -90°.
   • Alteratively, you can rotate by putting the DEIMOS hand paddle in manual mode, turning the mode selector to 0 (fast jog), then using the FWD or REV buttons to turn the instrument until you can access bay 3.
   These put the bay on the left and right hand sides of the instrument, respectively, when viewed from the rear of the instrument looking toward the telescope.
2. Appy band brake. Use the lever at the left front of DEIMOS to prevent rotation of the barrel and protect the drive motor from damager. See figure 1.
3. Remove Bay 3 rear cover. To access the Lantronix power switch, remove the cover shown in figure 2. Please note the following:
   • You only need a flat-blade screwdriver. A suitable flat-blade is available right by the DEIMOS hand paddle.
   • All fasteners are 1/4 turn captured.
   • Do not undo the allen bolts visible on the panel.
   • This panel "wraps around the instrument". In other words it will be sort of L-shaped when removed.
4. Cycle power. Use the rocker switch on the front of the Lantronix unit to turn power off. Wait a few seconds, then turn power back on. Figure 3 shows the Lantronix terminal server and the rocker power switch.
5. Verify communications. Execute the DEIMOS testAll script to confirm that the DEIMOS host computers are able to communicate with the Lantronix unit. If so, then proceed with re-installing the rear cover. If not, check cabling as described next.
6. Remove side cover. To access the cabling at the back of the barrel Lantronix, remove the side cover using a 5/16” T-handle hex key. Figure 4 shows the cover.
7. Check cabling. Inspect the cabling at the back of the Lantronix, including the coax cable and adapter. Confirm that all cables are securely plugged in. If none are suspect, you might try unplugging individual cables and plugging them back in. Figure 5 shows the cabling as seen when the side access panel has been removed.
8. Re-verify communications. Execute the DEIMOS testAll script again to confirm that the DEIMOS host computers are able to communicate with the Lantronix unit. If so, then proceed with re-installing the rear cover. If not, try another power cycle. If this fails to fix the problem, then the Instrument Technician should configure and install a spare Lantronix. Night staff should not attempt this repair.
9. Re-install covers. Getting the covers back on can be a little tricky. Seat all the 1/4 turn fasterners in their sockets first then go around turning them.
10. Release band brake. Don't forget when leaving: release the band brake, set hand paddle in computer mode.

Figure 1. DEIMOS band brake

Band brake. Push lever down to engage. Pull up to release.

Figure 2. DEIMOS electronics bay 3

Panel to be removed. Only undo the flat blade 1/4 turn quick release fasteners. Do not try to undo the hex key screws that are visible in the panel.

Figure 3. DEIMOS Lantronix terminal server

Lantronix terminal server in electronics bay 3.

Figure 4. DEIMOS electronics bay 3, side view

Side view of the panel which must be removed to access cabling on the DEIMOS barrel Lantronix unit. This requires a 5/16” T-handle hex key.

Figure 5. DEIMOS Lantronix cabling

View of DEIMOS Lantronix with side panel of bay 3 removed, showing cabling.