Is it possible to ever find out the exact changes in UPS package?
OS v6.1, v5.26 is working correctly. Since version v6.2 and v6.3 UPS does not communicate. Is connected via the serial port.
serial port setings: br: 2400, 8 data bit, 1 stop bit.

Does anyone have a similar problem or solution?

THX

edit: v6.4 not working

yes - same problem
works only in 5.xx - never got it running in 6.x

yes - same problem
works only in 5.xx - never got it running in 6.x

What do you use interface, what type of UPS?

Serial with UPC smart ups
works on 5.x never run in 6.x after upgrade

Serial with UPC smart ups
works on 5.x never run in 6.x after upgrade

Hey, and you even tried v6.1, the one I'm currently working.

we have Smart-UPS SC420 and Back-UPS BR1500GI FW:878.L3 .I USB FW:L3 connected to x86 boxes running 6.1 via rs232 and usb cable.all ok.

we have Smart-UPS SC420 and Back-UPS BR1500GI FW:878.L3 .I USB FW:L3 connected to x86 boxes running 6.1 via rs232 and usb cable.all ok.

In my opinion, v6.1 is OK. Have you tried the newer version of the OS (6.2 to 6.4)?

6.4 - all ok

I analyzed communication between UPC back-up and operating system
Mikrotik version 6.2 - 6.7 (UPS pack). I found out, that in these
versions there were added "a" letter question in the communication, but
UPS doesn't know its. The system doesn't communicate again after three
questions (with no reply). There is a similar problem with the letter
"-", but here at least system after three unsuccessful attempts
continues in sending other requests and system is still working.

I'd like to ask Mikrotik systems programmers , if it's possible, to
change evaluation of the "a" letter reply as well as in "-" letter replies.

Thanks to this correction system would communicate with old (or similar)
UPS version as my model is.

Thank you very much indeed,
best regards
BorgMcz