Ok, my last post was completely wrong!

First thing is, that the hand controller sends the pulse and not the software, so 3 wires to the hand controller should be ok, because a pulse command is just another RS232 command for the software.

I made a firmware update of my hand controller and tried again in a complete silent room.

With "Use Pulse Cmd" option "On" every pulse generates:

• [WARNING] PULSE STILL IN PROGRESS, POSSIBLE MOUNT JAM.
• no sound

With "Use Pulse Cmd" option "Off" every pulse generates:

• [Info] Moving toward West.
• [Info] Moving toward West halted.
• [WARNING] PULSE STILL IN PROGRESS, POSSIBLE MOUNT JAM.
• I hear the sound of the moving motor!!

So indeed, the pulse command works when "Use Pulse Cmd" option is turned "Off"! It still generates the warning and I was still not able to calibrate in my home with an artificial light and the wide angle lens of the ASI 120 MC, but I will try out with the guide scope in the next clear night.

I do not not know if the firmware update was important or not, because it is not easy to determine if the drive is executing a pulse command or not. I first had to switch off tracking and to shut down my PC before I was able to hear the noise of the moving motor. But I am glad to know that I am able to send a pulse command from the PI to the Nexstar.

Thank you very much for the useful hint!

Read More...