All,
I am comfortable designing a RB532 based AP and calculating power/solar requirements. I would like to use the UPS support in RouterOS to monitor battery voltage/current.
Does anyone have any suggestions of an inexpensive UPS with a db9 serial interface and compatibility with routerOS??
Thanks
A UPS implies that you’d be charging batteries, to power an inverter, to power the UPS full of batteries, to power a wall wart, to power the RB. That’s a lot of conversions and associated efficiency losses. You might be better off running straight from the batteries, and using the Serial Port Monitor and scripts to detect the state of your charging system, assuming it has outputs you could monitor.
It was implied, but I will be removing UPS electronics & only using them to monitor the state of my solar charging system and batteries. I would not use UPS for actual charging, only its interface to get a nice reading on battery statistics.
Almost any of the APC SmartUPS’s would probably work, if you can figure out how to remove the electronics and attach them to your solar array. You’d have to find the 117V sensing stuff and disable it since you won’t have line voltage, and you might have to disable the charging circuit so it doesn’t fight with the solar charger.
If your solar array has outputs, I still think it would be easier to sense those using the Serial Port Monitor stuff. All you’re really after is a low battery warning from the solar array, I suspect.
I guess what I really need is a small unit to monitor 2 analog channels (battery voltage, current draw) that would interface cleanly to my routerboard/routeros system. Any suggestions??
I Googled for “solar charge controller rs232” and got a lot of hits for controllers that could be remotely monitored. You’d have to write some scripts or have a central system poll/monitor each AP. With the central approach, you’d probably be able to graph the data using MRTG and have a history of your AP’s.
Find a controller you like and hook it to the RS232 port of the AP. Then use the serial passthrough feature to remotely access the MT’s serial port and talk directly to the controller.
Serial passthrough? That sounds most interesting, can’t find it in docs. v3?
It’s not documented in the PDF I have, but if you open a terminal window to your AP, look at the “special-logon” command. Basically you create a special user on the AP that links a telnet session directly to a serial port.
That is extremely cool. 
Rushing away to try it…
That does sound cool…iI am gonna have to try it myself!
Where do I create this user, and how do I tell routerOS to link this user to the serial port??
That sounds similar to using a Cisco router as a terminal server - telnet to port 200x for each async port to test/configure the analog modems.
I’ll definitely have a look at this since it could also be used for remote environment monitoring. Just tested it with a Linksys SRW224G4 switch and it worked fine.
To create a special-login user (the “serial-passthrough” feature):
Then login using the new users’ credentials over telnet or ssh, and you will be automatically connected to the serial device.
We are using this since at least early 2.8 versions (don’t remember for 2.7 and earlier). Be sure to use a rather recent 2.9 version - there were some where this functionality was broken…
Best regards,
Christian Meis
Regarding the usage for having a low-voltage warning for your solar panels you could do something without the need for an external machine connecting to a RS232-enabled charge controller.
If you can find a device (or do it yourself using a small microcontroller - that’s not too hard 
) that can trigger an output when the voltage drops below , you could use the sigwatch feature of RouterOS to trigger a RouterOS script whenever the voltage is rising below/above your configured monitoring voltage…
Best regards,
Christian Meis
Yeah, or even just a Schmitt trigger circuit.
I don´t recomend to install UPS in RB532 solar system, because the UPS have batery limited capacity and auto energy consumition.
The best solar AP configuration is a good solar panel and batteries. Use batteries with low maintenance, don´t use free maintenance.
Use the routerboard with DC current, directly connected to panel controller. Don´t use convertion DC/AC.
We have four solar repeater without energy problems. Of course, the weather place is very important for panel and battery calculator.
I tried changing serial port baud rate but it refuses??
[admin@MikroTik] port> set 0 baud-rate=9600
can not change port settings
[admin@MikroTik] port>
I am very interested in trying the rs232 access as I am looking at a Xantrex Link 10 Battery bank monitor that has a RS232 port and it would be great if the data coming from it could be accessed from the Mikrotik board. On another note I have a ethernet device that will ping the router and will reboot it if the RB fails or hangs up. It also has an input that can be used to send a signal or email, I think, from a dry contact closure such as a LVD off of a charge controller. See controlbyweb.com for info.
Mike
this would be so much simpler if the recent RB series boards had a LM sensor that could show supply rail voltage. what happened to /sys health anyways?
Having DC rail be measurable by SNMP would just make my solar life perfect, Ive been experimenting with an Omnitronix SL-12 and its working great, but this should not be a $500 solution…!
This serial passthrough is a fantastically useful feature, Im going to experiment with it using one of these cheap A-D converters, the protocol is a bit gnarly, but i think I can script it with perl via net-telnet. Awesome.
all charge controllers with serial ports are a bit too expensive and sophistacted for a simple one-panel 50W system. Ive found that LVD is a critical feature in a charge controller to not kill your battery, you’ll be down but not killing your battery.
any other solar users out there with tips?
Jon