SC420 does NOT beep

[Anonymous user]

Hi guys,

a complete UPS noob here - I am working with computers for more than 20 years but never needed a UPS up till now. I am setting up a FreeNAS and I've just bought today a used SC420I. I know it's on the small side but it was cheap and the battery seems to be brand new.

I was reading stuff on this site and others, downloaded the PowerChute sw, also the manual and looked for a smart signalling cable. So I am pretty much equipped 😉

When I've got home with this beauty I cleaned it, checked the battery connections and the voltage (13.2V) and it seemed quite a new battery. I also powered up the unit and hooked up a PC I am currently servicing. All good 'online' LED is green. After cutting off the power it is still good and it happily runs on battery for more than half an hour (it didn't go flat I just got bored and switched the power back on).

The problem is when on battery the unit does NOT beep. Is it right? It supposed to beep according what I've read. Could it be that it switched off through PowerChute?

And this leads us to my second question. If I want to test the UPS through my ThinkPad (server is not running yet) and check the settings then which PowerChute would I need? Agent/Server/Console? I mean just to connect and see the settings on the UPS (and not administering other PCs or servers)

Question #3 Which cable should I use between the laptop and the UPS and how to connect them? On the site there is the 940-0024 which is quite straightforward - apart from the fact that on the TP there is no serial port - but what to do with the AP940-1525A? Does the serial bit go to the UPS and the RJ45 to the TP or vice versa? I reckon it is the latter which case I still don't have a serial port on the TP.

I know they seem to be pretty dumb questions for a UPS pro but they are not covered in the user manual 

I would appreciate any help, thanks guys.

[Anonymous user · Accepted solution]

The SC420 supports having its alarm beeper shut off in software and someone may have done exactly that. Pressing the power button should produce a short beep as a response. By default it would beep when running on the battery.

If you don't get that short beep, it's possible that someone physically removed the beeper from inside the UPS.

Regarding monitoring software, you have a few options. Despite its low end status, the SC420 is still a Smart-UPS and as such, it speaks the widely supported UPSlink (or "APC Smart") protocol. You can use any of apcupsd, the long ago discontinued PowerChute Plus, or PowerChute Personal Edition to monitor, test and control the UPS. Or you can simply communicate with the unit by using the UPSlink protocol from within a terminal emulator, which might be the best thing to do if all you want to do is test it out. (The settings to use are a 2400 bit per second communication rate, 8 data bits, no parity, one stop bit and no flow control. Hyperterminal as included with Windows XP and prior works fine. If you are running a newer version of Windows that does not include Hyperterminal, you can use a program such as PuTTY instead.)

APC has documentation covering UPSlink very well on their web site. A quick search ought to turn up a fairly comprehensive PDF manual explaining all the commands.

Since you are just getting started, I would recommend PowerChute Personal Edition or PowerChute Plus (if you can find it -- I believe it's still on the APC FTP site somewhere).

When you get your FreeNAS running, I believe they still package software to monitor your UPS and ensure a safe shutdown of the server. The original FreeNAS (now known as NAS4Free) definitely included such software and it was very easy to configure.

Another program you may want to look up is APCfix. Despite the name, this is not an official APC utility. Its primary purpose is to reset a value known as the "battery constant". If you are sure your unit has a new battery, you will want to do this. That way you can be sure the unit won't shut down before the battery has truly become empty. This program's web site is in Russian, but it's still pretty easy to figure out what to download. (The program itself runs in English.)

The cable you want to use is the 940-0024. Variants with a letter suffix such as A, B, C or D are simply revisions to this cable and will work in the same way. If your laptop hasn't got an RS232 serial port, a USB to serial adapter will generally work just fine. The 940-1525 cable is for a different application and won't work with your SC420. You can buy the cable from APC, make one yourself, buy a cable from a third party or buy a used cable.

I have a much older Smart UPS 420 and it is an excellent UPS. I use it to back up power to my connectivity equipment, something that it will easily do for more than an hour and a half.

Hopefully this post has been helpful. Please feel free to mark it as such if that is the case. And don't hesitate to ask any other questions you might have.

[Anonymous user]

Thanks a lot William for taking the time! This is a very throughout answer I appreciate it 🙂

As the forum engine just lost my whole typed up comment I'll be a bit less detailed than I was before.

Last night I've run another 'cut off' test and found out that the unit starts to beep towards the end but quite irregularly and the beeps are distorted. BTW , I do have the switch-on, switch-off beep hence I've thought it's disabled which is kind of stupid, isn't it? 

I've found apcfix  yesterday when I was looking for some pin-out diagrams for the cables (BTW , if someone needs the cabling pin-out further down the line: one here and another one here. I'll make one myself probably tonight to see what's what.) Software wise APS's website is a bit confusing as if I look up the product first (SC420I) than only PC Business is offered for download in many different flavour but PE is only available from the main sw support page. Still needs to figure out the differences between Business (server/client/etc) and PE but I'll give it a shot when the cable's done. Also I've found the UPSlink stuff on APC's website, thanks again.

BTW looking for related stuff I've found APC UPS Daemon, check it out if interested.

So thanks again for the excellent write up 🙂

I've seen some firmware update on the product page (PowerNet MIB v4.1.7) why is that there for? This unit hasn't got management card slot or am I missing something?

[Anonymous user]

Why the heck does the forum engine delete the space after every word which is not in its dictionary?!?

[Anonymous user]

It sounds like someone programmed your SC420 to beep only when the battery was nearly exhausted. I think the threshold is around two minutes of runtime left, but that will vary depending upon how good the battery is. It's not unusual for the beeps to sound distorted or irregular.

PowerChute Personal Edition can only monitor a UPS directly attached to a single computer. It can't provide notifications to a network of multiple PCs that the power has gone out or guide more than one computer to a safe shutdown when the battery is nearly exhausted. PowerChute Business Edition (and Network Shutdown) basically add this capability. I haven't used Business or Network Shutdown very much, so I can't be of much more assistance than that.

On 4/24/2016 7:33 AM, cpufan said:

BTW looking for related stuff I've found APC UPS Daemon, check it out if interested.

That's what I called out as "apcupsd" in my original response to your post. 🙂 It is a great program and runs on just about any popular operating system. Network UPS Tools may also be useful to you, and may be what the FreeNAS developers are still bundling with their product for UPS management.

Your SC420 definitely does not support the use of a management card, and it does not have upgradeable firmware either. (The only way to attach a management card is by way of an external enclosure, such as the AP9600 or AP9604. And if you do that, the UPS will power itself off rather suddenly and rudely refuse to power back on until you disconnect the enclosure.)

I believe I'm correct in telling you that the MIB file offered for download is utilized with SNMP aware applications and that it serves to provide a definition of the traps returned by an APC SNMP management card, so that the software in question "knows" what it ought to do in response. Again, though, that's not something I've had a lot to do with and I could be wrong.

The issue with spaces being lost between words is a bug that comes up for users of Google's Chrome or Chrome/Blink-derived browsers. It seems not be to be a problem with Firefox. (I too have noticed that the issue is especially likely to come up when words aren't in the spellchecker's dictionary.) The forum software is a packaged solution seemingly known as "Communifire" and it seems a little bit on the half-baked side.

[Anonymous user]

Hi William,

good news thanks to your help I made a successful connection with aliens on Pluto the UPS.

Took out an old desktop from the cupboard and although PowerChute PE refused to acknowledge the UPS and complained that no UPS has been connected, apcfix done it for the first time.
The only issue is that with apcfix I cannot change the settings or reset to default, at least not with the demo version but I am sure I'll figure out something.

So thanks for the prompt help, really appreciated 🙂

EDIT: APCUPS Daemon config files states these settings in eprom - presumably mine is set to L=low battery

# Alarm delay
# 0 = zero delay after pwr fail, T = power fail + 30 sec, L = low battery, N = never
# BEEPSTATE 0 T L N (default = 0)
#BEEPSTATE T

# Low battery warning delay in minutes
# LOWBATT 02 05 07 10 (default = 02)
#LOWBATT 2