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I have Unitronics Jazz Jz-20-T40 PLC.

I have all the newest software and PLC system.

When i power ON my PLC, and then using USB i connect it to my laptop, connection is working fine and i can see PLC from laptop.

Then, when I download PLC Program to my Jazz PLC, it downloads normally, and as it should, PLC reboots.

On my other Jazz PLCs it turns ON again, and it's still connected to my laptop.

But, on this specific model, when i finish download, and try to connect to it again, it displays 4-5 messages that says restart U90, PC and so on.

When I try to connect to it again, I get same message. I tried to restart U90, still the same. I really don't want to restart laptop, so I tried to unplug and plug USB. It shows me that i don't have needed drivers for this device. I click update device software, it says it's already newest, as it should. Then i try to install from U90, it says that I already have it. Then I unplug and plug again, and everything works normally.

Every time I download, i need to unplug and plug USB twice, before I can again debug my PLC. It just needs to be reconnected twice, without installing anything at all. 

It confuses me a lot. Please help.

Thankful in advance,

Nikola Ljubinkovic

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  • MVP 2023

Hi Nikola,

It's a long shot, but I'm assuming that you have installed the usb drivers by using the button at the bottom of the PC Communication Port Settings window?  Controller/M90 OPLC Settings.  If not, try this and see what happens and advise back for further suggestions. You might have a few drivers in your system messing things up.



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Hi Ausman,

First to say this.  Thanks for quick answer.  I really like this forum and I'm very thankful for all the help I've been getting. I have never left without answer I came for. With that said, we can continue working on this small, but very annoying problem.

Yes of course I have installed my driver from that menu. I have also checked if I have any other driver that is messing things up, nothing is installed for U90 Ladder beside this one I already have. I used this same laptop with same drivers for many other unitronics PLC's, and I've used it after, and have no problems with it. I had something like 5-6 Unitronics PLC's after this specific one (Jazz) and had no problems with it. It confuses me.

I have also tried to install drivers on my old laptop that I never use, and this laptop is empty of all drivers and programs, it just have windows. I installed U90 and drivers, and I have connected successfully to exactly same PLC, everything works fine, and then I download one line of ladder code, with input and output, and same thing happens. Unplug/Plug twice, keeps working normally until next download, then same again. 

Also, sometimes, it takes more than two unplug/plug usb to get thing running. Few times, like 2-3, it has connected successfully to PLC, and worked for 5-10 seconds, and then crashed just like every other time. Yesterday, when I was testing other PLC's I tried really hard to get them to crash same way, I downloaded so many times, and i have disconnected them while download, after download, and nothing happens. It just displays errors that it normally should (because I'm disconnecting it WHILE download). 

My goal here is to find out what could I have done wrong to make this happen every single time, and to be able to download without interruption.

Best regards,

Nikola Ljubinkovic

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I'm have 3 main computers I use.

Windows 10 home is my main, but for PLC programming I mostly use one with Windows 7. I also have one with Windows 8.1.

All three are laptops, and I also have fourth one, with Windows XP and Vista. I have tried this on all of them, besides XP and Vista, it worked same on all laptops.

My Colleague has two PC's and one laptop all with Windows 7, I tried that on all of them, and I got same results. 

I should just mention, all my software is always up to date, my job requires me to always have all the latest software. Also, PLC is up to date, Bios, OS Version etc. All newest.

Problem didn't happen on some uptade, or something like that, because first thing that came to my mind was that some of the updates is not working properly, so i downgraded my laptops to version I was sure PLC has worked on. Again, same thing. 

This error happens to me on ethernet and USB.

Best Regards,

Nikola Ljubinkovic

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