6 How to Recover from a Probe Collision

If the red collision LED comes on brighter than its usual faint glow, or if you get the message ``No controller present'', you have had a probe collision. This is not a fatal problem, but it could put a halt to your observing program for a while. The electronic collision detector resets all the motor controllers to stop further probe motion whenever two probes make contact. A collision may be caused by a bad command such as moving all probes to the center simultaneously. A collision may also result if there is an electronic or mechanical failure that prevents a probe from moving. Sometimes static can scramble the brains of the stepper controller, causing it to move erratically.

1. Identify that there was a collision (as per above paragraph).
2. Turn Collision Override Switch (CXOVR) ON Yellow LED will come On.
3. Press Enterprise Reset Button.
4. `` G0100 '' -- To Restart Enterprise Program
5. `` A? '' -- To see if all probe controllers are alive. If not, call for help.
6. `` A^ '' -- to reload motor controllers if power was interrupted.
7. `` A< '' -- to retract all probes radially (fixes 99% of collisions)
8. Wait 5 seconds and Turn OFF CXOVR switch. The probes should have moved away from the collision. If the red collision LED comes on again, go back to step 1.
9. Wait 30 seconds for probes to retract radially.
10. `` A? '' should show all probes at the negative radial (1-) limit.
11. `` A> '' to retract all probes azimuthally.
12. Wait 30 seconds for probes to retract azimuthally.
13. `` A? '' should show all probes at the negative azimuthal (2-) limit.
14. `` AZ '' to zero all probes at this position.
15. `` A* '' -- to reinitialize all probes at limits. It is usually best to do this twice.
16. Ready to Go again after ``Setup Done'' message from Enterprise.

6.1 Things That Make Probe Collisions

• Astronomer Error
• Problematic Probe Targets
• Corrupted Coordinate Buffer
• Electrical Glitch of Stepper Controller
• Stepper Motor Loses Track of Steps
• Electronic Failure
• Power Outage