[V9.0.1 OS Update failure]

Thank you very much, it was bad usb to rs232 converter. It's ok now.

[V9.0.1 OS Update failure]

It's 7-8 years old plc, and I can't update o.s with. U90 6.6.28 . 

Please tell me how can I do it.

[V9.0.1 OS Update failure]

The updating i began and stopped, I mean not finished, bootsrap mode, I have tried another com,pprt but same results, I'm tired

[V9.0.1 OS Update failure]

I have a problem with updating o.s with u90 ladder to m91-2-r34, please help