PDU Communication Modules Explained: Gateway, Controller or Daisy Chain?

In conventional rack PDU solutions, communication is often hardcoded: one Ethernet port per PDU or a fixed bus structure, typically paired with over-engineered hardware. Schleifenbauer disrupts this paradigm by offering modular, hot-swappable communication options. You choose the intelligence that fits your infrastructure strategy.

1. Gateway Module For Centralised Control and Scalability

Use the Gateway Module when:

• You require a centralised energy management platform via the free DCEM software (EnerTree Platform).
• You want to group and manage PDUs using a single IP address per ring of up to 100 PDUs.
• You operate in large-scale environments (up to 10,000 PDUs), such as hyperscale data centres, cloud facilities, high-density colocation sites, or AI/HPC data centres.
• You prefer not to have embedded software or a web interface on each individual PDU — centralising all intelligence in the EnerTree Platform instead.

Benefits:

• EnerTree Platform: Licence-free software running on a server or desktop.
• 1 IP = 100 PDUs → minimal network load and scalable to 10,000 PDUs per system.
• Supports advanced features like reporting, auto-detection, group switching, alerts, and full integration with any DCIM package.
• Fastest refresh rate: 1x per second.
• Ports: Ethernet + 2 databus ports + 2 USB-A + optional second LAN via USB.
• Enhanced security: Combine with Daisy Chain Modules, which have no independent LAN access → physically segmented network areas.

Typical topology:

• One or more PDUs with a Gateway Module.
• Optional: combine with up to 99 Daisy Chain Modules in a ring configuration.
• By offloading PDU intelligence to the EnerTree Platform (running on a server, VM or standalone PC), rack-level compute load is reduced while enabling advanced analytics and scalable control.

2. Controller Module For Conventional Management with a Built-in Web Interface

Use the Controller Module when:

• You want a web interface accessible per PDU (EnerTree Lite).
• You manage standalone racks or small groups of PDUs where local access and control is preferred.
• You already use DCIM tools and want direct integration at the PDU level.
• You manage up to 100 PDUs per ring under one IP, or assign individual IPs (if preferred).

Benefits:

• EnerTree Lite is embedded (no external installation needed).
• Dedicated web interface per PDU.
• Full support for alerts, thresholds, reporting, logging and real-time monitoring (1x every 5 seconds).
• Ports: Ethernet + 2 databus ports + 2 USB-A + optional second LAN via USB.

Typical topology:

• One or more PDUs with a Controller Module.
• Optional: combine with up to 99 Daisy Chain Modules in a ring configuration.

3. Daisy Chain Module For Cost-Efficient Expansion Without IP Overhead

Use the Daisy Chain Module when:

• You’re expanding an existing PDU ring.
• You prefer to maintain one IP address per ring.
• You don’t require a local web interface on each PDU but still need full monitoring via a central Gateway or Controller module.

Benefits:

• Cost-effective: no dedicated Ethernet port, no built-in intelligence → reduced price.
• Data relayed via the databus to the central module (Gateway or Controller).
• No direct LAN access on Daisy Chain PDUs → improved network integrity.
• Hot-swappable and zero-touch provisioning.
• Up to 99 units per ring (in addition to one intelligent module).

Flexible PDU configurations with Gateway modules

Schleifenbauer PDUs with a Gateway module offer maximum flexibility when building a Databus ring. Within a single system, up to 100 PDUs can be connected and managed via one IP address.

There are two common configuration approaches, depending on your project requirements.

Single Gateway architecture

In the most commonly used setup, one PDU is equipped with a Gateway module and acts as the central communication point. The remaining PDUs are fitted with Daisy Chain modules and connected via the Databus ring.

This approach is efficient, cost-effective and requires only one IP address to monitor and manage all connected PDUs.

All Gateway architecture

For projects where a uniform hardware setup is preferred, all PDUs can be equipped with Gateway modules. In this configuration, EnerTree assigns one PDU as the communication master, while the remaining PDUs are logically grouped within the same Databus ring.

This allows for simplified logistics and maximum flexibility without changing the physical hardware.

Software-defined flexibility

A key advantage of the Gateway module is that the role of each PDU is not fixed in hardware. Whether a PDU operates as the communication master or as part of the Databus ring is defined within the EnerTree platform.

This makes it possible to adapt system architecture at any time, without replacing modules or modifying the installation.

Summary: Which Module for Which Scenario?

Module	Gateway Module	Controller Module	Daisy Chain Module
Use Case	Large-scale, centralised management	Small-scale or traditional setup	Managed via Gateway or Controller
IP usage	1 IP per PDU or 1 IP per ring	1 IP per PDU or 1 IP per ring	Managed via Gateway or Controller
Web interface	Central via EnerTree Platform	Individual per PDU	Managed via Gateway or Controller
Max PDUs per Ring	100	100	99 & 1 Gateway or Controller
Energy Management	Full centralised control via EnerTree Platform (up to 10,000 PDUs)	Embedded EnerTree Lite (up to 100 PDUs in system)	Relayed via Gateway or Controller

Security & Future-Readiness

• All modules support up to 32 sensors.
• Zero-touch provisioning for quick deployment.
• Full integration with common protocols: SNMP (v1/v2c/v3), REST API, MODBUS/TCP, Syslog, CLI, SQL export, etc.
• Strong security features: AES-256 encryption, Active Directory, secure boot, HTTPS, and more.

Comparison Table

Functionality	EnerTree Platform	EnerTree Lite
PDU 5.0	Gateway Module	Controller Module
Maximum number of PDUs in the system	10,000	100
Maximum number of supported rings	100	1
Maximum number of PDUs in 1 ring (one IP address)	100	100
Refresh rate of measurements	1 per second	1 per 5 seconds
Device Management
Automatic detection of newly added PDUs	✓	✓
Mass configuration	✓	✓
Grouping devices & merging measurements	✓	–
Supports Schleifenbauer Generation 2 and 3 PDUs	✓	–
User Management
Custom roles & rights, group management, etc.	✓	✓
Control & Alerts
Group switching	✓	–
Adjustable thresholds for all measurements (alerts)	✓	✓
Data
Dashboard view	Advanced	Basic
Report generation	Advanced	Basic
Scheduling reports	✓	–
Data export to files or databases	✓	✓
Security
Logging and auditing	Advanced	Basic
Updates and backups (configuration, logs)	✓	✓

PDU 5.0 Communication Modules: Gateway, Controller & Daisy Chain

No fixed display required anymore!
Fixed displays are vulnerable in demanding environments such as data centres, prone to dust, damage and obsolescence. That’s why Schleifenbauer opted for a more robust, future-proof approach in the design of the PDU 5.0: an NFC-based Display App.
This allows you to securely read local measurement data via your smartphone or tablet — no network connection or login required. It makes the system more reliable, durable, and user-friendly.

More information about NFC and Display App

If you have any questions or would like assistance in making your choice, please contact our sales team at sales@schleifenbauer.eu or by phone on +31 73 523 0256.