I have a 750 VA APC Smart UPS and a RB1100.
I got connected the serial port from UPS to Console RB1100 and in Winbox when I try to add the UPS on serial0 it say:
Couldn’t add New UPS - port’s channel is already in use (6)
Is there another serial connection on rb1100?
you may need to disable the serial console first, as it’s using that port:
http://wiki.mikrotik.com/wiki/Serial_Port_Usage
OK, I typed: /system console disable 0
Now it let me add ups on serial0 but it show as offline and all red text.
Is there any tutorial on how to setup APC UPS on serial?
Still cannot comunicate with the UPS. 
Model: http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SUA750RM1U
Problem solved.
The serial cable was the problem.
I changed the pins like in here
http://pinouts.ru/DevicesCables/apc_smart_cable_pinout.shtml
and all worked out. 
RB1100 doesn’t boot with RS232 APC UPS (Smart-UPS 620I) connected. If I connect UPS after boot ROS, everything working fine. ROS version 5.5, latest firmware.
Any idea?
I have RB1100 and smart UPS connected with APC RS232 cable, I upgraded boot loader to version 2.38 and the RB1100 doesn’t boot anymore.
Do you think it might be same problem with RB1100 and Smart UPS connected, It have worked without problems up to now before upgrading boot loader and I have rebooted RB1100 several times with Smart UPS connected.
system - routerboad - settings: Enter setup on delete key.
Default is “any key” and it is wrong.
Do you think, that RB1100 is actually detecting UPS on RS232 as console input and RB1100 goes into setup mode.
My RB1100 is on remote location otherwise I would disconnect RS232 already, I’ll tell someone to disconnect RS232 cable from UPS and hopefully if RouterOS will load, I will change Enter Setup on DEL key.
Thanks, ludvik, solved the problem, by your suggestion. 
hello
dear friend
i have a RB433AH and a Tatung-TCU200 plus
i want to send SMS bye serial port on routerboard
how to install a configur it ?
plz help me