DISCONNECTION WITH IOPTRON COMMANDER - Forums

Topic starter

May 22, 2025

HELLO EVERYONE

I have an ioptron cem 120 EC2. Randomly the ioptron commander application disconnects saying that it can't find any devices anymore.
Looking in the USB peripherals I see the mount connected.
The only way to reconnect the application is to turn the mount off and on again.

Below I send you the communication that there was between me and ioptron, from bottom to top, my answers in bold and italics

Maybe some of you have in mind how to solve the problem.

thanks

good morning and sorry for the late reply. The remote PC I use is an Intel Nuc.

Should I disable bluetooth?

The problem occurs even if the mount remains on in parking, it is not a problem due to the meridian flip.

thank

Since you are using Sequence during imaging, do you know if these drops happened during meridian flips?

Dear Ricardo

Yes, I read the log files and sent to the development team for analysis.

May I ask if there is any Bluetooth related COM port? Is the computer a Eagle system with updated system?

Hi All

I keep having connection problems between the ioptron CEM 120 EC2 mount and my PC with the ioptron commander app.

Attached you will find a zip file that includes various logs, some with the old commander update, the most recent logs have the latest commander update.

As you can see it always fails in the #GUT phase (I don't know what it means), then it tries to restart and fails.

I can tell you that when the mount is disconnected, I still see that the USB device is connected and active.

The only way to reconnect it to the ioptron commander app is to turn off the mount and turn on again.

the other thing I don't understand is that the GPS has never given me the "ok" signal, it always remains "on". The GPS module is placed in such a way that it receives well

I can tell you that the cause of these problems cannot be the USB cable because I have already tried 3 cables all fine.

I updated all the drivers as you told me directly from the FTDI site.

the ioptron commander app is updated.

tell me how to proceed. Considering the value of this mount I would ask for maximum support, thank you

If I have to change the motherboard, know that I will request it through Giuliano Monti of Tecnosky

The Green one, FTDI chip website

Hi John & Kevin

after 6 days without disconnections, the ioptron cem 120 EC2 has disconnected again.

My first question is:

where do you recommend I download the FTDI driver?

directly from the direct link of the single driver in red or on the official site FTDI in green?

Hi, Riccardo,

Glad you worked it out with newer version Commander. Thanks for updating!

good morning,

I confirm that I had the previous version of ioptron commander. With the new one it seems that the problem has been solved.

The mount has been connected to the PC for 4 days now. Before it would disconnect even after 2 hours.

however I will evaluate the RS232 interface which still requires USB to the Pc

The log file is for 9.13. Did the new drive and Commander solve the issue? If it still the same, you can send the board to us for service/replacement.

According to development team, RS232 port is the most reliable connection.

Hi Kevin and John

I have installed the latest ftdi vcp drivers, the firmware versione is the 230305 and both axes 212104 ( are the latest).

Now I have install the latest of ioptron commander 9.2.0.1

In attachment the file log, abort during 02:49

Hi Ricardo,

If you connect the mount to a computer via the USB port on the mount base directly, it should not related to the USB hub connection.

The only possibility is the USB B port physical connection issue or the assigned USB COM port. Could you please try install the latest FTDI VCP driver? What is the firmware version, ASCOM Platform, Commander Version and Computer operation system?

Could you send us the Commander Log file as well?

Hi, Riccardo,

Sorry to learn the issue. Is your mount with 3X USB port and 2 USB2.0? if so, you may send both the input board and the USB hub to us for test and replace the faulty, free of charge except S&H. Your shipping address and proof for purchase are needed for an RMA.

Hi

I have owned an ioptron CEM 120 EC2 with double encoder since January.

I immediately had problems with connecting the mount to the PC via the USB port.

It happens that every now and then (even during a night sequence) the mount suddenly disconnects and is no longer displayed by the ioptron application.

I can tell you that the power supply has no problems because the mount remains on in tracking on the object.

I tried changing USB cables (short, long, gold plated) but I did not solve the problem.

I tried changing the USB port on the PC without solving the problem.

Instead, connecting the mount via a LAN network cable, there are no disconnections, but I would like to use it with all the features at maximum and the USB is convenient.

I saw online that you have released an updated card to avoid these problems with the USB port, is it true?

Do you have any advice for me? Can I replace some components?

thanks in advance, Riccardo

andrea tasselli

Frequent contributor

May 22, 2025

My solution, as it were, is NOT to use the USB as it is a piece of crap. I use wifi instead. Different mount, GEM28 here.

Riccardo Civati

Topic starter

May 22, 2025

how can i use wifi or lan?

andrea tasselli

Frequent contributor

May 22, 2025

I don't know about the LAN but for the wifi you just connect to it from the mount's hotspot (will have some weird alpha-numerical name) using your PC wifi connection and then use the Commander to connect to the mount via wifi. Easy as pie…

Riccardo Civati

Topic starter

May 23, 2025

andrea tasselli:
I don't know about the LAN but for the wifi you just connect to it from the mount's hotspot (will have some weird alpha-numerical name) using your PC wifi connection and then use the Commander to connect to the mount via wifi. Easy as pie...

my problem is that it is a remote PC, that PC is already connected via network to be able to access remotely, so I don't think I can connect to the wifi network of the mount

andrea tasselli

Frequent contributor

May 23, 2025

Then use the LAN access point. Inverted cable, not straight through, I think…

Riccardo Civati

Topic starter

May 23, 2025

andrea tasselli:
Then use the LAN access point. Inverted cable, not straight through, I think...

I have the classic RJ45 cat 6 cable, is that what you mean?

andrea tasselli

Frequent contributor

May 23, 2025

No, I think is called reversed or cross-over RJ45 cable.

AstroDivers

May 23, 2025

We have two CEM120, one in Spain, one in Australia. So both remote.
Same problem on both.

The only way to solve this, other than to disturb the blessed people in the observatories, is to have a smart plug that is able to turn off/on the mount.
Otherwise there were time where we had to spam reconnect for 30 minutes, with PC restart spam (just out of desperation).
Pc restart at times seemed to short the time needed to spam the reconnect.

Only with the implementation of a smart plug with remote the use of this mount has been easier.
Get a smart plug to connect to your phone and try to forget about this.

I know the feeling.

Helpful Supportive

Rainer Ehlert

Jan 17, 2026

Hi,

I know this topic is as old as Mathusalem.

From the first day on I did connect both of my CEM 120EC2 via RS232 port to the PC via a USB to RS232 adapter and never ever had a disconnect except when the smart Windows does make an update it screws up the driver version 3.8.41.0.. but as I know it now, I revert to the mentioned 3.8.41.0 driver for the StarTech USb to RS232 adapter.

https://www.startech.com/en-us/cards-adapters/icusb232pro

And BTW iOptron just told me again that the RS232 communication via an USB>RS232 adapter is more reliable. Email to me from 15/01/2026

📷 image.png

As far as I know iOptron does deliver with the mounts the corresponding cable at least my mounts came with a RS232 cable with DB9 connector to RJ9 (4wires only).

You can even make your own cable.

📷 image.png

Helpful

Ashraf AbuSara

Jan 18, 2026

Interesting. I have been having this issue with my CEM70ec-Nuc and I can’t figure out what the issue is. I changed a gazillion cables. What’s interesting is when I change to a new cable, things work for a few weeks or a month before the issue creeps up again.

Most recently I just changed a USB-B to USB-A cable with ferrite chokes and it seems to perform the best so far. Only one disconnection in a month, and I am not sure if it is even the same problem.

Still a very annoying issue.

Engaging

Riccardo Civati

Topic starter

Jan 18, 2026

I had a very long discussion with ioptron, but unfortunately, nothing was resolved in the end.

My recommendation (if you don't already) is to always turn off the mount at the end of each session and turn it back on at the beginning.

I solved it this way and have never had any problems again.

What I noticed during all my tests was that the problem occurred only when the mount was idle. During normal tracking operation, it never gave me any errors.

I changed cables, power supplies, and USB ports. Also try spraying contact renewal fluid; maybe the contacts get dirty over time.

Or it's just a data traffic issue...

Riccardo

Helpful Supportive

Ashraf AbuSara

Jan 18, 2026

Goodness I jinxed myself. Happened mid session last night. Lost 6 hours of moonless pristine imaging time.

Gonna try doing what you suggest Riccardo. Might be the last straw before I give up and drop serious $$$ on an AP or 10micron. Which is a real shame because it has been tracking beautifully so far.

Rainer Ehlert

Jan 18, 2026

Before spending big bucks why not try with a USB>RS232 adapter which cost less then 50 dollars? 🤔

If even the development department in 2018 told me (as well as 3 days ago) that the RS232 is more reliable then their USB connection the something is really wrong with iOptron.

The problem is nowadays you hardly find a PC with a RS232 port…

I have never had trouble with the StarTech USB > RS 232 and my mounts. Looks like the USB connection through the USB>RS232 is more robust then the used chip on the iOptron mount motherboard.

Another nuisance is their USB 3.0 port electronic board. Since new I had a lot of trouble so I decided to thread in a USB 3.0 cable through the mount and put a separate USB 3.0 Hub on the DEC axis. Since then the trouble is gone.

OK, I have to add that I added an additional 35mm high spacer between the telescope plate and the DEC axis in order to get a greater angle for the maximum 14° after the meridian and this spacer has 2 channels for taking up cables.

📷 NHSA_DEC_Plate_2.jpg📷 NHSA_DEC_Plate_3.jpg📷 NHSA_DEC_Plate_4.jpg📷 NHSA_DEC_Plate_1.jpg📷 NHSA_DEC_Plate_5.jpg

Helpful

Ashraf AbuSara

Jan 18, 2026

I am a bit confused about the RS232 port. I don’t have one on my CEM70ec or on my miniPC. Are you saying use a USB>RS232 cable, and then find a PC with an RS232 port to connect to?

Well Written Engaging

Rainer Ehlert

Jan 18, 2026

Ashraf AbuSara · Jan 18, 2026, 08:12 PM
I am a bit confused about the RS232 port. I don’t have one on my CEM70ec or on my miniPC. Are you saying use a USB>RS232 cable, and then find a PC with an RS232 port to connect to?

No,

Either a 100% RS232 cable on one side with a RJ9 and on the other side a DB9 connector or an USB>RS232 adapter and then a cable with DB9 to RJ9 connector.

DB9 to RJ9 cable

USB to RS232 adapter

📷 image.pngNow that you mention a USB to RS232 cable FTDI has one adaptable to RS232 communication

https://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS232_CABLES.pdf

Yes you are right, the CEM 70 does not have a RS232 connector and here we are talking about the CEM 120 XXXXX

📷 image.pngBelow a view of the main board of a CEM 120XXXXX

📷 image.png

Riccardo Civati

Topic starter

Jan 18, 2026

I also had the problem with the mount connected only via network cable, so I would rule out USB, RS232, and USB ports.

It could also be a bug in the Ioptron Commander application.

The USB hub on the DEC axis has nothing to do with the USB control.

In my CEM120 EC, I removed the USB hub and power hub module. I run the 12-volt and USB cable from the Pegasus Ultimate, which I place on the telescope. It's a perfect setup for the remote.

Helpful Concise

Rainer Ehlert

Jan 18, 2026

Riccardo Civati · Jan 18, 2026, 09:04 PM
The USB hub on the DEC axis has nothing to do with the USB control.

I know. I just mentioned it so we can judge how serious iOptron is taking this problem. I still ahve the first USB board and in the meantime they have version 3 and they SELL it, not even exchange it free of charge after charging us more then 7000 dollars per mount and in the meantime it is 9500…

Some poeple swear of the the good iOptron After Sales service and others just are riding a Merry Go round with the iOptron After Sales service

I was a pioneer with the very first two CEM 120EC2 mounts and for 2 years ironing out their BUGS in firmware and software and for that they let me stand in the rain alone…

🤬

Related discussions

CEM70 Disconnects via USB

Hi All, I've been having a recent issue with my CEM70 dropping connections. I have the CEM70 connected via USB to a mini PC. It is powered by a 12v 5a adapter that is plugged into the wall. (via power brick) I've run this same config for abou...

Similar CEM device disconnection issue; troubleshooting steps may apply.

Nov 26, 2023

iOptron commander 9.20.1

Hi iOptronerds, Anybody else having or had this problem, not possible to slew “Counterweight Up Pointing” as Pointing state is greyed out, with commander 9.20.1 and how did you solve it. I have CEM 120EC2 mounts and before upgrading to 9.20.1 I had 9...

iOptron commander application issue similar to USB device disconnection problem.

Jan 29, 2026

EQ6-R Pro with PHD2 on a Mac Computer

Was thinking of upgrading my mount to the EQ6-R pro, I use a MacBook Pro right now, and was wondering if PHD2 will recognize the mount through USB and be able to guide the mount. I have a ZWO120mm mini guide camera which is recognized in PHD2 so I wa...

iOptron mount connection issues may relate to USB/driver problems author faces.

Nov 15, 2023

2600MC Pro disconnection issues

Hi all, Having an issue with disconnects every since getting a new 2600MC Pro. I am using an ASIAIR Plus and have had over a year of use with a DSLR without this issue ever occurring. This my 3rd night of using a new 2600MCP and on each night have ha...

Disconnection issues with astronomy equipment; may share troubleshooting solutions.

Nov 25, 2025

iOptron Commander Log File Viewer Application

In the course of trying to sort out some unusual behavior I was getting from my iOptron GEM28 mount, I consulted the log files produced by iOptron Commander, the Windows application and ASCOM driver that iOptron has published for use with its mounts....

Addresses iOptron Commander connectivity issues; relevant to troubleshooting mount problems.

Sep 6, 2023