Ioptron CEM communication problem

I have an Ioptron CEM40. I loaded the Ioptron Commander driver. SGP recognizes the mount. I set the mount to the zero position, and set Ioptron Icommnander to the zero position. I entered the target coordinates in SGP. I hit “slew” in SGP. The mount went off in the wrong direction, hit the limits, and actually burned out the board before I could hit the power switch. (The mount is on the way back to Ioptron.) The actual position of the mount was not communicated to SGP by the Ioptron driver, or SGP did not query the mount. Any advice on preventing this from happening again?

I use SGP all the time to find and center objects with plate solves with my Astrophysics mount…never any problems!


That’s unfortunate. SGP doesn’t really do any “diffing” between between positions, even if SGP didn’t know what the position was we only send it to a RA/Dec to go to. However it’s likely that the mount wasn’t really sure where it actually was without and ended up in “lala land”. Being at the “Zero” position and knowing where it is in the solar system are 2 different things.


Now that I think about it, when it had worked, I first did a plate solve and sync in SGP with the mount in the zero position before slewing to the target. That is not necessary with the AP mounts.

I have CEM120EC2. The Ioptron commnander sometimes does not set the actual time and date and then this happens. It think, this is not related to SGP. This is problem is very random (maybe 1:100) and I cannot say when it happens (I cannot reproduce it). I have a friend and he has the same problem. Ioptron says that it is not possible to happen, but sometimes it happens :frowning:

If your “Zero Position” is pointing anywhere near the pole then that will 100% cause pointing weirdness for almost any GEM. When pointing at the pole it’s very difficult for the mount to tell where it’s actually located at since slewing the RA doesn’t actually change the RA. You should always slew off a few degrees before syncing the mount.


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I had the same thing happen several times with my CEM 60. Come to find out, the GPS had not acquired the necessary satellites and my date and time were wrong. Most likely, it will say a 2013 date when the software was first introduced. If, after a time, the GPS does not acquire the right date and time, you can sync it to computer on the CEM ascom driver. Look on your hand controller to see if it is the correct date before proceeding. I almost suffered a similar fate with the scope hitting the mount. Hope this helps any CEM users as there was allegedly some Ioptron update to correct this.

The time and location were correct in ICommander. I think the problem occurred because I synced the mount in the zero position pointed at the rotational axis of the earth, which does not tell SGP where the mount is. Nevertheless, it should not have burned out.


I fully agree to all that has been said above.
The fact is that so many different situations can occur that you can never be 100% sure that the mount will not contact the limits.
For this reason, two years ago, I installed limit switches myself on my CEM120EC2, as shown on the following link.

In fact, they so far never activated, even after an intense use of the mount remotely in Spain from France over the last 9 months.
I hope this could be useful to you.