Please note, there are reports that you must use UPSTYPE smartups on the slave even if the master is using UPSTYPE dumb. This is apparently some bug in the new dumb driver.

In this configuration, the shutdown will be initiated by the master. It is also possible to specify BATTERYLEVEL, MINUTES, and TIMEOUT configu- ration directives in the Slave machine that will cause the slave to shutdown before the master. This can often be useful if the slave is less important than the master and you wish to reduce battery power consumption so that the master can remain up longer during a power outage.

Variation on the Master/Slave Configuration

It is also possible to have a Master/Slave configuration where the Slave is powered by a different UPS (or any other power source), but is nevertheless controlled (i.e. shutdown) by the master. The setup would be identical to the Master/Slave configuration files shown above. The only difference is where the slave actually receives its power. In effect, apcupsd does not know or care where the power really comes from.

A Sample NIS Slave Configuration Using the Net Driver

As opposed to the old master/slave mode demonstrated above, you can turn any computer into an NIS slave by configuring with the NIS network driver turned on --enable-net. The difference is that the NIS server has no explicit knowledge of the slaves. The NIS server makes its information available via the net (NIS), and the NIS slaves read it. When the NIS server is going to shutdown, it makes the information available to any NIS slave that polls it, but the NIS server does not explicitly call each NIS slave as is the case in the Master/Slave networking described several sections above.

Running in this configuration, you can use any computer with apcupsd running the Network Information Server (NIS) as the server. The NIS slave simply uses the NIS information to decide when to shutdown. This is a much simpler mode than the older master/slave code mentioned above.

The main apcupsd (NIS server) is connected to the UPS and has NIS turned on, but the configuration is a simple standalone as in the section A Sim- ple Configuration for a SmartUPS. It doesn’t matter how the UPS is connected to the computer (serial, USB, ...).

For the NIS slave computer, you will have a configuration that looks some-

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APC UPS control system Variation on the Master/Slave Configuration, Sample NIS Slave Configuration Using the Net Driver
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UPS control system specifications

APC UPS (Uninterruptible Power Supply) control systems are vital components for ensuring uninterrupted power supply and protecting critical equipment from power interruptions, surges, or fluctuations. Designed by Schneider Electric, APC UPS systems are renowned for their high quality and reliability. They utilize advanced technologies and features to suit diverse applications, from home offices to large industrial settings.

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