How Software can Help

Close-down software is essential when servers are expected to run unmanned, as usually happens when they are left running overnight. Close-down software will respond to a communication from the UPS and will typically broadcast a warning message to users, then wait a specified period of time before performing an orderly close down of the system. Depending upon the facilities offered, the software may offer the ability to closedown applications as well as performing a file system shutdown.

Monitoring software, on the other hand, falls into the category of 'nice-to-have'. It provides a display, usually graphic, which shows battery levels, mains input voltage, remaining runtime, as well as UPS status and other information, depending on the functionality provided by that particular manufacturer. Monitoring information can usually be delivered via SNMP over the network, (whilst closedown communications are almost always via a local serial link in case power loss has affected hubs or routers). UPS devices showing an exception condition will be highlighted on an SNMP monitoring station.

All but the least expensive modern UPS offer some form of communication port, mostly in the form of a 9-pin 'D' connector. On the more basic models this consists of 'dry' or 'volts-free' contacts which can be read by monitoring software via a serial communications port. These give basic information such as 'Mains OK'; 'On battery' or 'Battery low'. Monitoring software, on the other hand, requires more sophisticated signalling in the form of a serial communications interface. The two types are often distinguished by the terms 'dumb' and 'smart' interfaces.