LX200 GPS Focus control software advice Please

[BlackWidow]

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:question:

Andrew