Editing Uninterruptible power supply (section)

==Communication==
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[[Power management]] (PM) requires:

# The UPS to report its status to the computer it powers via a communications link such as a [[RS-232|serial port]], [[Ethernet]] and [[Simple Network Management Protocol]], GSM/[[GPRS]] or [[USB]]
# A subsystem in the [[Operating system|OS]] that processes the reports and generates notifications, PM events, or commands an ordered shut down.<ref name="tldp_aen187">Raymond, Eric Steven. [http://tldp.org/HOWTO/UPS-HOWTO/x142.html#AEN187 UPS HOWTO, section 3.3]. The Linux Documentation Project, 2003–2007.</ref> Some UPS manufacturers publish their communication protocols, but other manufacturers (such as [[American Power Conversion|APC]]) use [[proprietary protocol]]s.

The basic computer-to-UPS control methods are intended for one-to-one signaling from a single source to a single target. For example, a single UPS may connect to a single computer to provide status information about the UPS, and allow the computer to control the UPS. Similarly, the USB protocol is also intended to connect a single computer to multiple peripheral devices.

In some situations, it is useful for a single large UPS to be able to communicate with several protected devices. For traditional serial or USB control, a ''signal replication'' device may be used, which for example allows one UPS to connect to five computers using serial or USB connections.<ref>{{cite web|author=Generex|quote=Multi-XS is an active RS232 data switch, designed to handle serial communications of one UPS with up to 5 / 10 computers|url=http://www.generex.de/generex/download/manuals/manual_MULTIXS_en.pdf|title=Multi-XS User Manual|access-date=2011-11-14|archive-date=2012-01-27|archive-url=https://web.archive.org/web/20120127190246/http://www.generex.de/generex/download/manuals/manual_MULTIXS_en.pdf|url-status=dead}}</ref> However, the splitting is typically only one direction from UPS to the devices to provide status information. Return control signals may only be permitted from one of the protected systems to the UPS.<ref>APC AP9207 Share-UPS, User Manual, pp. 6–7, ''Port 1 is called the Advanced port because it supplies smart signaling, which provides the advanced capabilities available to a server running PowerChute plus software. The Advanced port provides full access to the Computer Interface port of the UPS.'' '' Ports 2–8 on the rear panel of Share-UPS are called Basic ports because they supply simple UPS signaling for On Battery and Low Battery conditions in the UPS.'' {{cite web|url=http://www.apcmedia.com/salestools/ASTE-6Z5QCB_R0_EN.pdf |access-date=November 14, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120424231213/http://www.apcmedia.com/salestools/ASTE-6Z5QCB_R0_EN.pdf |archive-date=April 24, 2012 |title=Share-UPS User Manual}}</ref>

As Ethernet has increased in common use since the 1990s, control signals are now commonly sent between a single UPS and multiple computers using standard Ethernet [[data communication]] methods such as [[TCP/IP]].<ref>An example of an Ethernet UPS controller: [http://emersonnetworkpower.com/EN-US/PRODUCTS/MONITORING/FORLARGEDATACENTER/ADVANCEDMONITORING/Pages/LiebertIntelliSlotWebCardCommunicationsInterfaceCard.aspx Liebert IntelliSlot Web Card Communications Interface Card] {{Webarchive|url=https://web.archive.org/web/20160413232114/http://emersonnetworkpower.com/EN-US/PRODUCTS/MONITORING/FORLARGEDATACENTER/ADVANCEDMONITORING/Pages/LiebertIntelliSlotWebCardCommunicationsInterfaceCard.aspx |date=2016-04-13 }}</ref> The status and control information is typically encrypted so that, for example, an outside hacker can not gain control of the UPS and command it to shut down.<ref>APC Application Note #67 {{cite web|url=http://www.apcmedia.com/salestools/VAVR-5ZJSVU_R2_EN.pdf |access-date=November 14, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120424231216/http://www.apcmedia.com/salestools/VAVR-5ZJSVU_R2_EN.pdf |archive-date=April 24, 2012 |title= APC Network Management Card Security Implementation}}</ref>

Distribution of UPS status and control data requires that all intermediary devices such as Ethernet switches or serial multiplexers be powered by one or more UPS systems, in order for the UPS alerts to reach the target systems during a [[power outage]]. To avoid the dependency on Ethernet infrastructure, the UPSs can be connected directly to the main control server by using a GSM/GPRS channel also. The SMS or GPRS data packets sent from UPSs trigger software to shut down the PCs to reduce the load.