Combine hardware, software and cabling into a networking hub that connects IT and industrial networks for increased reliability, security and troubleshooting ease.
A MDC is hardware, software and cabling that serves as a networking hub.
Plant operators are using Ethernet at all levels of manufacturing, from sensors and I/O blocks to controllers and up to manufacturing servers, switches and storage. It’s
essential to ensure the linkage between devices and systems is secure, protected from environmental factors such as heat or dirt, and optimized to speed diagnostics — all
while reserving the ability to isolate the networks when security threats to production arise.
The centerpiece that brings this all together is a Micro Data Center (MDC), a partial, single or multiple rack/cabinet that houses rack-mounted servers, switches, storage,
uninterruptible power supply (UPS), backup systems and DIN-rail mounted devices. Poor industrial network installation can generate unacceptable downtime risks (see Figure 1).
The MDC is designed to provide the bridge between the corporate and the industrial networks to provide these functions:
- Maintain network uptime.
- Provide the ability to segregate networks.
- Manage network security.
- Speed changes and troubleshooting.
- Provide ease of installation.
Let’s review the elements of an MDC and examine the benefits of deploying this technology in an industrial automation environment.
Micro Data Center Characteristics
Many companies are centralizing network responsibility for all computer networks under the IT department as proprietary control networks are replaced with standard,
unmodified Ethernet. This has created conflicts between IT and manufacturing because of differing goals. An MDC helps to separate the networks and reduce conflict
points between networks and the enterprise teams that support them, and optimize them for manufacturing.
An MDC is a combination of hardware, software and cabling that serves as an end-to-end computer, store and control network hub. It houses a complete data center
infrastructure in a single space – electronic devices, patch fields, cable management, grounding/bonding, power and copper/fiber cabling – yet is sized to serve
the demands of a manufacturing environment.
The MDC is a new concept, representing the next phase in the transition from tower computers systems in a manufacturing environment to rack and cabinet-based
deployments, with the ability to serve a variety of enterprise purposes. For example, the MDC can act as a stand-alone system that runs manufacturing applications
- Process and event monitoring, process historian, production tracking and overall equipment efficiency (OEE) reporting.
- Control network, outer loop control, recipe download.
- Quality control, material handling, maintenance, lot tracing, and asset management.
- ERP integration (scheduling, reporting, material consumption, etc.).
In addition, the MDC can take the form of a networking hub that has no servers, existing primarily to tie cabling and switches together. For large manufacturing
facilities or remote locations, an MDC can serve as a data collection node that passes manufacturing data up to the enterprise (such as Store and Forward). An MDC
also can house Virtual Machine (VM) systems for high reliability and efficient server utilization.
From a logical architecture perspective, the MDC is positioned between the manufacturing floor and the enterprise data center. The preferred method to achieve
separation is a demilitarized zone (DMZ) that is used in conjunction with a firewall to prevent direct traffic between the enterprise and manufacturing networks.
Other methods, such as a single firewall and VLANs, can be employed with lesser degrees at a lower cost.
Key elements of a robust MDC include:
- Housing – racks and cabinets.
- Equipment layout.
- Network cabling – media selection and security.
- Power and grounding.
- Cable management.
Housing – Racks and Cabinets. A rack or cabinet typically houses MDC elements in a centralized modular form factor. One main difference between a rack and a
cabinet is protection: a cabinet offers greater security and environmental protection (from both dirt and workers) because of its four walls and a locking door
mechanism, versus the open environment provided by a rack. A rack is more open allowing greater cooling.
For harsh environments, the MDC can be housed in a NEMA-rated hardened cabinet with the proper cooling and environmental protection.
The housing (see Figure 2) needs to accommodate all equipment, patch panels and cable managers while providing a growth factor of 30% to 50% to accommodate future
expansion. For small MDCs, half-height racks or cabinets may be sufficient, while large installations might require full-size or multiple racks/cabinets.
- Cabinets. In general, cabinets are designed for servers or switches.
- Racks. These can be either a two-post or four-post design. Typically, a network rack with shallow switches can fit a two-post design. Larger and heavier equipment
is best handled by a four-post design, especially if mounting servers with rails.
Equipment Layout. Equipment layout in a rack or cabinet depends on the number, weight and type of components as well as segregation. Common design practice locates
enterprise network equipment at the top and industrial network equipment at the bottom – with DMZ firewalls positioned in the middle of the housing.
Thermal loads in an industrial MDC application are quite low, typically less than 25% of that experienced in an enterprise data-center environment, assuming normal temperatures.
This reduced heat load, coupled with the extended operating capabilities of industrial-rated switches, greatly diminishes the need for active cooling solutions in many industrial
Network Cabling — Media Selection and Security. Ethernet media can be fiber optic cabling or copper cabling. Regardless of the media selection, using a patch panel for connections
in an MDC provides for essential testing and diagnostic points between equipment and field connections, critical for fast troubleshooting.
Power and Grounding. Robust and clean power must be supplied to the MDC. The incoming power feed typically includes a UPS and one or more Power Outlet Units (POUs) to distribute
power where needed. POU voltages range from 100V to 125V or 220V to 250V, depending on the region of the world, with currents ranging from 15A to 30A.
Power connectors can be straight blade or twist locks. Popular International Electrotechnical Commission (IEC) configurations are C13 to C14 and C19 to C20. Additionally, POUs can
include intelligent features such as power and environmental monitoring to aid in troubleshooting and diagnostics that are communicated via network to displays.
Grounding the MDC is critical to optimizing performance of all equipment located within the MDC unit, reducing downtime caused by equipment failures and reducing the
risk of data loss.
Cable Management. Proper wire management is essential for reliable connectivity and to speed troubleshooting, diagnostics and moves, adds and changes. Two areas
in the MDC require wire management:
- Input and Output to/from the MDC – Horizontal Cable
- Within the MDC – Patch Cables
Bend radius control, identification, strain relief, and slack management can create challenges leading to risks of down- time and inefficient troubleshooting.
An MDC helps you maintain robust, integrated and secure networks, bridging the gap between the corporate and industrial networks while maintaining flexibility to
disconnect the network links quickly in the event of a problem.
A well-designed MDC protects the integrity, availability and confidentiality of control and information data. It facilitates the connectivity from the plant
floor up to the enterprise, giving greater visibility into the manufacturing processes to identify problems, optimize processes and plan for the future.
"A Micro Data Center is hardware, software and cabling that serves as a networking hub."
Figure 1. Micro Data Center (MDC) is a partial, single or multiple rack/cabinet that houses rack-mounted servers, switches, an uninterruptible power supply, backup systems
and DIN-rail mounted devices.
Figure 2. A rack or cabinet that houses MDC elements needs to accommodate all equipment, patch panels and cable managers, with room for future expansion.