Issue with B&R PLC and ACOPOS drives

Hi everyone.
I'm having an issue with B&R PLC and ACOPOS 1016 drives. I'm getting a fault on the HMI "servo fault". There are three exactly the same servo motors and drives on the machine,so I connected different motor to the same drive (same fault stays on). I connected "faulted" motor to different drive and the fault is still there. No matter if I change drive and/or motor I keep getting the same fault.
I thought that maybe the drive was bad and no matter when it is connected the system will not clear the fault, so I took the same model drive from another machine to try it but that did not help, still the same fault. Even worse happened, when I put that drive back into the other machine it now keeps blinking red error LED. LED stays on for about two seconds and off for 0.5 second (after boot-up). Why would that be. I did not change any settings, etc. on that drive. Has anybody ever had a situation when something else on the machine caused "servo fault" than servo motor and/or drive?

I do have B&R Automation Studio software but I have never used it, so I have no idea how to connect to the B&R PLC. Any help with that would be much appreciated. It's X20BC 0083 (PLC model).

First, any drive error would have a number you could easily search in the Automation Studio help file and up to 4 lines of 80 characters of error text, so you saying HMI says "servo fault" is a pretty uninformative. If your HMI program doesn't let you see these details, you can see them in SDM using any laptop and a browser by going to http:\\<PLC_IPaddrees>/SDM.

The ACOPOS LED blink codes are in the help under [Hardware -> Motion Control -> ACOPOS -> Technical Data -> Status Indicators -> LED Status (GUID 8112a11c-1f37-4c71-9286-9b5f06e623bc)]. You can jump directly there by using View -> GoTo Page (or Ctrl+G) and pasting in that GUID.
The LED code you describe is during boot phase stating that network communication is active. You can get it stuck there if you have the node number set incorrectly (same as another drive or to a value not used by the program). You may also want to check the AC114 LED status codes under [...Technical Data -> ACOPOS Plug-in Modules -> AC114 -> Status Indicators (GUID 05b148aa-b6d9-478f-af6a-9aac0b0a536d)]. This is also the same blink code you'd expect if a drive is doing a firmware upgrade.

ACOPOS getting firmware updates can take a while to turn back on and they get firmware upgrades/downgrades anytime their current firmware doesn't match the one for the project stored on the PLC. Moving drives back and forth to different machines programmed at different times may cause the drive to go through this firmware upgrade/downgrade every time you move it, so don't assume that a drive you swapped in and out that doesn't startup green at the same time as the other drives is faulty; you might just have to wait a minute for the firmware.