LX200 GPS Focus control software advice Please

[BlackWidow (Mardy)]

I am looking for some simple software that will allow me to adjust the focus on my LX200GPS with the meade electric focus system. I found that stary night pro will allow for this in steps so that I do not have to use my hand controller all the time..

however I am looking for just a simple focus program that will allow me to set the focus in steps rather than the pressing a button and getting different results (chasing the focus). I think if it can be set to 1 step or 2 steps etc it will be far easyer to find good focus.

does anyone know of a program like this

Regards
Mardy

[Barrykgerdes]

I have not seen any LX200 software that includes a focus control but there must be a program somewhere. Writing a program should not be difficult as the necessary commands are already part of the Meade protocol.

I must add the facility to the program I wrote.

Barry

PS Added to LX200DM.exe 25/02/12

[AndrewJ]

I have a focus controller in my PEC editor, that will work as a normal pressn hold focus or as a "PulseFocusser", but there are caveats.
The Meade focusser is a simple DC motor, it has no feedback loops.
As such, there is no way to know where it is or how far it moved.
There is an undocumented :FPsDDDD# "pulsefocus" command, where you tell the focusser to move a set time at the current speed.
This command has a bug unless you run patched firmware,
but even when it works correctly, the distance moved depends on load and orientation, ie its still very variable.

Andrew

[Barrykgerdes]

Hi Andrew

I just added a simple focus control to my LX200 driver program. It has IN/OUT controls and you can select fast or slow. I don't know what it does on a GPS model but on the LX200 "FAST" gives a polarised 2 Volts on a meter depending on whether it is in or out and Slow gives about 1 volt on the meter. I don't have a focuser to test with and I did not have time to rig a small motor.

Controls #:F+#, #:F-#, #:FF# and #:FS# are common to LX200 classic and GPS. These are all I used. The LX200 has its own driver U14 but this IC is only ever used if a Meade focuser is plugged in.

I did not look at the waveform but I imagine it is PWM

As you say there is no actual position indication.

Barry

PS I had a terrible job testing it. My computer would not find COM 1 or 2. I ended up testing on another computer. The USB/COM adaptor and cable had packed it in. It must have got damaged when my foot got tangled in the cable and near pulled the computer of the desk.

[AndrewJ]

Gday Barry

The LX200GPS focusser is a simple 12V DC motor running with a PWM feed via a 5ohm current limiting resistor from a mosfet HBridge.
The basic functionality gives 4 speeds, but it can be "patched" if reqd to change the duty cycles. Not much point unless you get a feedback loop.
Several people have just araldited a cheap chinese caliper onto the unit
and then read the caliper via serial comms.
As to the GPSs. The new function is :FPsDDD#
s is + or - and DDDD is millisecs
It is a send and forget command, so gets much better granularity on run time, but is still load and orientation dependent for absolute movement.
Unpatched, the current command only goes one way

Andrew