Dome Control

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Revision as of 05:16, 23 October 2011 by John (Talk | contribs) (Sirius Dome for CDK20N)

The domes at Moore and Mt. Kent observatories have their own control systems designed to interface with the electromechanical hardware supplied by the dome manufacturer. The esstential cdesign elements shared by all domes are

  • Rotation encoder
  • Rotation motor controller
  • Shutter status monitor
  • Shutter motor controller
  • Software connected to the telescope control system

This page is a description of the dome control hardware and software highlighting similarities and differences between the systems for the two Sirius domes housing the CDK20's, the Ash dome for the RC24, and a refurbished dome for the CDK700.

Sirius Dome for CDK20N

The original Sirius electronics control dome rotation and the opening and closure of the upper and lower shutters. A mechanical switch such as shown in this schematic


will apply 12 VDC power to one of two lines that select the direction of rotation, or similarly opening or closing the two shutters. In computer controlled operation there is a relay system in parallel with the manual switch, such as shown here:

400 pix

with the power for the relays provided by the "COM" power of the dome electronics. Note that "COM" is not ground, but the common 12VDC form the battery power of the system. Fuses and circuit breakers protect the motors from overload, and the control board is designed so that most operations are safe. In this respect, there are limit switches on the shutter motion that turn off power to the motors with the shutters are fully open or closed. There is no hard wired logic to insure that thelower shutter is closed before the upper shutter drops down over it, however.

At CDK20N we have a relay box mounted on the dome wall containing 6 socketed industrial relays with 12 VDC coils. The relays are wired such that the application of the "COM" voltage to a control line will cause the relay to close with the same effect as the corresponding switch.

600 pix