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Can't make apcupsd to see UPS via USB-to-serial cable

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Occasional Visitor

I am trying to make my APC 1000INET work with the AC68U directly via the genuine DB9-to-USB cable. It works perfectly fine with apcupsd on a Linux box but doesn't on the router.

Once device is connected, here is what I see in the system log /tmp/syslog.log
Dec  7 17:28:14 kernel: usbcore: registered new interface driver usbserial
Dec  7 17:28:14 kernel: USB Serial support registered for generic
Dec  7 17:28:14 kernel: usbcore: registered new interface driver usbserial_generic
Dec  7 17:28:14 kernel: usbserial: USB Serial Driver core
Dec  7 17:28:14 kernel: USB Serial support registered for GSM modem (1-port)
Dec  7 17:28:14 kernel: option 3-2:1.0: GSM modem (1-port) converter detected
Dec  7 17:28:14 kernel: usb 3-2: GSM modem (1-port) converter now attached to ttyUSB0
Dec  7 17:28:14 kernel: usbcore: registered new interface driver option
Dec  7 17:28:14 kernel: option: v0.7.2:USB Driver for GSM modems

My settings are similar to what I used on a Linux box /opt/etc/apcupsd/apcupsd.conf
UPSTYPE apcsmart 
DEVICE /dev/ttyUSB0

and finally running apctest shows that there is still no communication with the UPS.
2020-12-07 15:29:18 apctest 3.14.14 (31 May 2016) unknown
Checking configuration ...
sharenet.type = Network & ShareUPS Disabled
cable.type = Custom Cable Smart
mode.type = APC Smart UPS (any)
Setting up the port ...
apctest FATAL ERROR in smartsetup.c at line 155
PANIC! Cannot communicate with UPS via serial port.
Please make sure the port specified on the DEVICE directive is correct,
and that your cable specification on the UPSCABLE directive is correct.
apctest error termination completed

I suspect this is because router treats it as a modem and if it is true, how can I change this? I don't really use USB modems and having an UPS connected is more important for me.

Jeffrey Young

Very Senior Member
Getting this to run has been on my todo list for a while. Have not started, but I have saved this link for when I start the troubleshooting phase. Hopefully it is of value for you...



Occasional Visitor
I am using PL-2303 HXD cable and I suspect according module is missing from the standard firmware set :\

Jeffrey Young

Very Senior Member
The kernel modules that you need are not loaded at boot time by the router. They are on the router's firmware though as per the link I posted above. You just need to load them.

The three modules that you need are found at the following locations on my RT86U. The kernel version will be different on the RT68U, but otherwise they should be in the same spot;


Edit your apcupsd startup script and load the above modules in the order listed above.

Jeffrey Young

Very Senior Member
Checking with my 68U, the modules you are looking for are in;


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