Terminology & Concepts

This article defines key terms and concepts used throughout Synaccess PDU documentation. While this guide assumes some technical familiarity, it is designed to clarify PDU-specific terminology that may not be widely known outside of power infrastructure or facilities engineering.

Core Terms

PDU (Power Distribution Unit)

A hardware device that distributes AC power to multiple connected devices, typically servers, switches, or lab equipment. Synaccess PDUs support remote control and monitoring capabilities via web UI, CLI, and API.

Switched PDU

A type of PDU that allows individual outlet control — meaning each connected device can be turned ON, OFF, or power-cycled remotely. Switched PDUs are ideal for remote troubleshooting, power sequencing, or automated resets. Most Synaccess PDUs fall into this category.

Metered PDU

A PDU that provides power usage monitoring (voltage, current, power, energy) at the outlet, bank, or unit level. Metered PDUs do not always allow outlet switching — monitoring and control capabilities may or may not be combined. Synaccess offers PDUs that are both switched and metered for full functionality.

Outlet

An individually controllable AC power port on the PDU. Each outlet can typically be turned ON, OFF, or power-cycled (rebooted) independently or in groups.

Bank

A physical grouping of outlets, often tied to a single circuit or internal relay. Turning off a bank disables power to all outlets in that group simultaneously. Banks are hardware-defined and cannot be modified.

Group

A logical grouping of outlets that can span across banks. Groups allow batch control (e.g., reboot all outlets in “Group A”) and are user-configurable.

Reboot

A two-step operation where an outlet is turned OFF for a defined delay, then turned back ON. Useful for cycling power to connected devices without requiring manual intervention.

Startup State / Power-On Behavior

Defines how each outlet behaves when the PDU is powered on or restarted. Options may include:

Always ON
Always OFF
Restore previous state
Staggered delay (used to reduce inrush current)

Sensor

An external module (e.g., temperature, humidity, contact closure) that can be connected to supported PDUs for environmental monitoring and automation triggers.

Schedule

A recurring or one-time event configured to control outlets automatically at specific times or intervals. For example:

Power-cycle Outlet 3 every Sunday at 2 AM
Turn OFF a group of outlets every night at 10 PM

Webhook / Event Trigger

Available on supported models. Allows the PDU to send real-time notifications (e.g., via HTTP POST) when a threshold or state change occurs — such as temperature exceeding a limit or outlet failure.

CLI (Command Line Interface)

A text-based control interface accessible via SSH, Telnet, or serial console. The CLI provides quick command access for managing configuration, status, and outlet control without using the web interface.

API (Application Programming Interface)

A set of programmatic HTTP endpoints that allow external systems to monitor and control the PDU. Synaccess supports a RESTful API with JSON responses and authentication.