INDI Celestron SCT Focuser driver is included with libindi >= 1.8.8 Under Ubuntu, you can install the driver via:
sudo add-apt-repository ppa:mutlaqja/ppa
sudo apt-get update
sudo apt-get install indi-bin
Celestron SCT Focuser driver is used to control Celestron Motorized Focuser when connected directly to a computer via USB. This driver should not be used if the focuser is connected directly to the mount. When connected directly to the mount, simply use the Celestron mount driver and it would automatically recognize and connect to the focuser.
Do not use Celestron SCT driver if the focuser is connected directly to the Mount direct via AUX cable. Instead, use the Celestron Mount driver to control the focuser.
This driver can be used to :
- Move the focuser to an absolute position (specific absolute steps)
- Focus IN and OUT using selected steps (relative position)
- Abort the focuser motion
- Set backlash.
- Calibrate the focuser position.
In order to connect to the focuser you just have to plug the USB cable and power up the focuser. Under Connection tab, you can set the Serial Port especially if you have multiple serial ports connected to the same PC. It is best to use Serial Assistant Manager to designate a permenant port (e.g. /dev/focuser) to this device.
You need to calibrate the focuser when using it for the first time. The calibration parameters are stored on the focuser itself so it can be re-used later. To begin the calibration process:
- Ensure the focuser is installed correctly and that the screws are tightend correctly.
- Set the starting point of the focuser halfway/center. This is very important, try to get it to halfway as close as possible.
- Click Start Calibration and then monitor the Calibration Status until the calibration process is complete.
- If the focuser does not stop on its own, make sure to check and address common mechanical issues.
- After it is complete and successful, you can begin to utilize the focuser.
You may set pre-defined presets for common focuser positions in the Presets tab.
- Preset Positions: You may set up to 3 preset positions. When you make a change, the new values will be saved in the driver's configuration file and are loaded automatically in subsequent uses.
- Preset GOTO: Click any preset to go to that position
If the focuser fails to calibration, here are some tips shared by Mr. Joe Larch. Thank you Joe!
- To basically check the function of the calibration process, I removed the focuser and stopped the rotating part with a firm grip a few seconds after the start of the calibration process (focus motor starts rotating counterclockwise). The focuser then changed its direction of rotation due to the calibration process. After a few seconds I slowed down the rotating part again with my hand. The calibration process was completed and I was sure that the focuser was working properly.
- The problem that the focuser did not work at the first start was the poor clamping of the plastic part on the C8-fokuser spindle. The metal part of the focuser that is supposed to clamp the plastic part (transition to the spindle) is too immobile/rigid despite the fully tightened clamping screw, so that the focuser does not reach an end or start position during the calibration process. The motor noise does change its frequency when the focuser reaches the start or end position, but the resistance is too low to complete the calibration process in the respective direction of rotation.
- The problem could be solved in a simple way. The brass sleeve of the focusing spindle was wrapped 3x with a Tixo tesa tape. The metal sleeve with the gear wheel that holds the plastic sleeve (already screwed in) was removed from the focuser. In order to connect the plastic sleeve with the brass part, which is wrapped with Tixo tape, without slipping, a few drops of super glue were spread on the inside of the plastic sleeve and the sleeve was then pushed onto the brass part. After a few seconds, the focuser part with the gear wheel and the plastic sleeve was well, but not completely permanently, connected to the spindle.
Finally, the focuser (motor and connections) was pushed onto the part with the gear wheel and screwed onto the other end with the fixing nut.
- The calibration process necessary for Stellarmate/EKOS could now be started. The focus motor (C8 focuser at the starting point) then rotates approx. 42,000 steps to the left (counterclockwise), reaches the "end position" and then changes the direction of rotation. When the start position is reached, the focus motor stops after approx. 42,100 steps (+100 step = backlash) and the calibration process is successfully completed
There are no known bugs for this driver. If you found a bug, please report it at INDI's Issue Tracking System at Github.