I have purchased the APC SURT3000XLI-CH UPS and hope to establish communication with the Unraid system. However, I am unable to achieve this through direct connection. I was wondering if anyone who owns the same UPS has any solutions

It connects right up connecting with usb. Check the apc that modbus us enabled.

If that doesnt do it, check the apc firmware is up to date.

Edited August 19Aug 19 by Veah

On 2026/8/19 at PM6点40分, Veah said:

连接USB时连接得很顺畅。检查一下我们启用的modbus启用的APC。

如果还不行，检查一下APC固件是否是最新的。

Are you using the same model of UPS as mine? My UPS firmware is the latest version, and I am using the official cable to connect it to the NAS. In the UPS settings of Unraid, I have set various options but it still cannot be recognized. It is worth noting that the APC backups I purchased before can be recognized

yes. I set my ups settings like these and it worked.

edit: also, don't use the serial cable. use a usb cable.

Edited August 20Aug 20 by Veah

23 hours ago, Veah said:

是的。我把UPS的设置都设置成这样，效果很好。

补充：另外，千万别用串口线。用USB线。

Thank you. I'll give it a try. What kind of USB cable do you use? It seems like the official one only has a serial port cable. Did you use an adapter or a directly purchased USB cable

I use a plain A to B usb cable like you might have from a printer.

If the usb cable does not work, i found a thread here that has good information that may help.

On 8/22/2026 at 6:40 AM, Veah said:

If the usb cable does not work, i found a thread here that has good information that may help.

Are you sure you are using this UPS? I purchased a USB cable with the same pinout, and I was able to achieve normal communication by connecting to the USB port on a Windows computer (using the official PCSS software). However, it is still not recognized in Unraid

APC Smart-UPS RT 3000VA, 220V

SURT3000XLI-CH

Oh no, that is not what I am looking at here, mine does not have a display like that. I am so sorry.

15 hours ago, Veah said:

哦不，我这里看的不是这个，我的显示器没有那样的。我很抱歉。

It's okay. I still want to thank you very much