Uninterruptible Power Supply - Communication

Communication

Power management (PM) requires

1. The UPS to report its status to the computer it powers via a communications link such as a serial port, Ethernet,GSM/GPRS or USB
2. A subsystem in the OS that processes the reports and generates notifications, generates PM events or commands an ordered shut down. Some UPS manufacturers publish their communication protocols, but other manufacturers (such as APC) use proprietary protocols.

The basic computer-to-UPS control methods are intended for one-to-one signalling 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 Universal Serial Bus 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. 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.

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. 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.

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 main control server by using GSM/GPRS channel also. The SMS or GPRS data packets sent from UPSs trigger software to shutdown the PCs to reduce the load.