Is there support for APC Back-UPS RS 1500MS2?

[shmerl]

Looks like Debian might retire apcupsd: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=810396

Is there support for APC Back-UPS RS 1500MS2 in nut?

[jimklimov]

Can't say TBH, so far nobody reported that model as tried - neither in issues, nor in HCL or DDL collections. You would have to try.

Note there are reports of APC devices with USB support made after 2010 slowly deprecating standard USB HID and going for Modbus over USB or one of many proprietary protocols APC created or bought along with smaller fish on the market. The "Modbus over USB" part may require building with our fork of libmodbus (can be a statically linked build) until that upstream (not too active either) accepts the patches: https://github.com/networkupstools/nut/wiki/APC-UPS-with-Modbus-protocol

[shmerl]

Is libmodbus dead upstream or otherwise, can they accept these changes?

UPDATE:

From the looks of it, it's somewhat active: https://github.com/stephane/libmodbus/commits/master/

I can give it a try, but if this isn't upstream in libmodbus, not sure Debian maintainers will want to maintain the fork or patches on top of upstream for this.

[jimklimov]

They are semi-alive, took well over a year to accept the contributor agreement form. Did not get to the PRs yet, AFAIK, but I did not really check for a long time.

The point about statically linking with the forked libmodbus is thus significant for packagers: this becomes a somewhat clumsy step in building NUT for their platform, but the results are private to the ultimate driver(s) provided with NUT - no extra files to conflict with the packaged upstream library.

[shmerl]

I'm not sure if Debian will even consider static linking. It seems to be not the common approach they take.

If the fork is significant in its own right, may be it should be separately packaged.

[jimklimov]

Could be, did not consider that much yet, hoping the upstream will come back from slumber :)

[EchterAgo]

I tried apc_modbus with my "Back-UPS RS 1500G FW:878.L5 .I USB FW:L5 (USB VID/PID 051d:0002)" but it seems there are no Modbus USB report descriptors and you can't enable it in the device either.

   0.042475     [D3:modbus] match_function_regex: matching a device...
   0.042579     [D2:modbus] match_function_regex: failed match of ProductID:    2
   0.042609     [D3:modbus] is_usb_device_supported: checking if this driver can support USB device VID:PID 0x051D:0x0002
   0.042640     [D4:modbus] is_usb_device_supported: checking table entry for VID:PID 0x051D:0x0003 (custom init handler is NOT available)
   0.042679     [D4:modbus] is_usb_device_supported: POSSIBLY_SUPPORTED: known vendor ID at least
   0.042710     [D2:modbus] _apc_modbus_usb_callback: Matched American Power Conversion Back-UPS RS 1500G FW:878.L5 .I USB FW:L5  (USB VID/PID 051d:0002)
   0.042744     [D2:modbus] _apc_modbus_usb_callback: Checking American Power Conversion Back-UPS RS 1500G FW:878.L5 .I USB FW:L5  (USB VID/PID 051d:0002) report descriptors
   0.042803     HIDParse: LogMax is less than LogMin. Vendor HID report descriptor may be incorrect; interpreting LogMax -1 as 255 in ReportID: 0x00
   0.042833     HIDParse: LogMax is less than LogMin. Vendor HID report descriptor may be incorrect; interpreting LogMax -1 as 255 in ReportID: 0x00
   0.042864     [D1:modbus] _apc_modbus_usb_callback: No Modbus USB report descriptor found
libusb_open for device #12 failed: Entity not found
_modbus_rtu_usb_connect: failed to get HID descriptor: Input/Output Error

Maybe we just fail getting the HID descriptor at all? I'll have to check. Will take me a while to set up debugging. I want to generally test apc_modbus on Windows and I want to figure out how to use my device with nut. Sadly the thing does not work with usbhid-ups either. IIRC PowerChute also installs some driver that prevents proper HID communication. I'll try connecting that UPS to my Linux box too.