Reduce data centre asset liabilities.

How you implement RFID monitoring is critical to the performance of the system.

Harting_Data_Centre_AppWith regular headlines about the latest cybercrime attack stealing important or commercially sensitive data, the physical security of IT equipment is often overlooked. One area in particular is the almost casual theft of small pieces of equipment from the racks. For example, the latest helium filled 10TB hard drive represent a €700  (£600stg) investment and with up to 22 drives used in a 4U storage array, loss through theft can be substantial.

The constant monitoring of what equipment is located inside the data centre has additional benefits not only in terms of security but also in managing cooling air-flow requirements and power consumption, which support growing need to demonstrate compliance with Green IT initiatives.

In response, data centres have been increasingly looking for cost efficient solutions for key asset management. Data Centre Infrastructure Management (DCIM)* is an emerging holistic management approach that combines traditional data centre equipment and facilities with monitoring software for centralized control. DCIM includes physical and asset level components and by combining both information technology and facilities management it raises the effectiveness of a data centre.

RFID has been seen by many as a key element to providing real-time monitoring of component location within the data centre. By installing passive RFID tags on every removable component of the rack data centre systems integrators and site operations managers can easily use them not only to record locations but more information about the device than they could before with standard asset tags.

But how you implement RFID monitoring is critical to the performance of the system.

Portable hand-held RFID reader systems have a very small UHF read range and only offer a slightly better performance than relying on paper records or barcodes because it requires employees to walk down aisles and identify the piece of equipment and its location. This is a very time-consuming task and as such is not undertaken very often. It also relies on the competence and integrity of the operator carrying out the check.


Fig 1

Up until now it has been unrealistic from a physical location point of view to directly integrate even the most compact passive RFID UHF patch antennas into existing data centre server rack arrays.

Typically, 4 antennas would have to be separately mounted either side of the front of each server rack, in both the upper and lower areas and carefully positioned to ensure there are no gaps in the RF field coverage. Correspondingly, with such an arrangement it would also be necessary to utilise multiple readers, resulting in excessive installed cost

Harting now have the ideal solution to remove this higher cost multiple patch antenna and reader arrangement with its innovative Ha-VIS RFID LOCFIELD® coaxial cable waveguide antenna.

They can be directly integrated, with insulating spacers, onto the rear side of the front access door of each server rack. Only one of these Ha-VIS RFID LOCFIELD® antennas needs to be fitted for a fully installed 45U sever rack. By fitting in an extended S-shape design (See Fig. 1) you can achieve the best possible RF field coverage of the complete rack. In conjunction with a single reader which has the required power to match the correct read distances, it can register passive RFID tags that provide specific item identification within a rack and additional sensor functionalities e.g. detecting empty or occupied slots, thus minimizing the complete data centre system installation cost.

The Ha-VIS RFID LOCFIELD® is a traveling wave RFID antenna consisting of a coax cable that—when plugged into the antenna port of a Harting UHF EPC Class1 Gen 2 reader—conveys the reader’s RF signal along the cable’s copper core and to the antenna’s far end, where a coupling element draws the RF wave out and onto the cable’s exterior. When that signal reaches the reader, a metal protecting shield prevents the interrogator from receiving its own signal and interfering with its performance. N.B. The Ha-VIS LOCFIELD ® antenna should not be mounted directly onto a metal surface but raised-off slightly with insulating spacers.


Fig 2 – Harting HA-VIS RFID LOCFIELD® antenna

By its functional nature the Ha-VIS RFID LOCFIELD® antenna facilitates real-time monitoring of movements in and out to the rack enclosure and is available in different lengths up to 10 metres and is 5 millimeters in diameter. If used with a high-powered reader, such as Harting’s Ha-VIS RF-R500 long range reader transmitting a signal of 4 watts (36dBm), it can read passive EPC Class 1 slot Gen 2 transponders located up to 2.5 metres away radially over its entire length.

Put simply Harting’s Ha-VIS RFID LOCFIELD® antennas allow you to identify what is in a data centre rack, its population status and where a specific item is located.

* DCIM was originally defined in the US and describes a methodology of IT and facilities management.
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Measuring gas cylinder temperature during filling


Infrared temperature sensors from Calex Electronics have been used with success for over 7 years by a leading provider of packaged gas for measuring the temperature of gas cylinders as they are filled.

When a gas cylinder is filled and the pressure increases, the cylinder will warm up. The temperature of the surface is monitored for several reasons:

• The target pressure is compensated so the amount of gas filled is corrected at a standard temperature, typically 15ºC.
• The temperature is monitored as the cylinder valves are opened. If the valve is opened correctly a drop in pressure and therefore temperature is observed before rising again as the cylinder is filled. If the temperature drop is not detected then filling is stopped as there could be a problem in opening the valve.
• If multiple cylinders are filled simultaneously, the highest and lowest filling temperatures of the batch are monitored and if the difference between these two temperatures is too great, filling can be stopped.

One PC151MT-0 sensor is aimed at the side of each gas cylinder.

The customer previously used magnetic probes to measure steel cylinder temperatures, however problems were encountered when non-magnetic aluminium alloy and composite wrapped cylinders were used. Infrared temperature measurement was investigated and found to be successful due to the sensor’s fast response time (240 ms), 4-20 mA output for connection to analogue inputs on the customer’s PLC, and ability to measure the temperature of the surface of wrapped cylinders through the plastic wrapping.

The cylinders are painted and sometimes icy, so satisfactory results can be obtained with the low-cost, fixed-emissivity PyroCouple series of sensors, which has a linear analogue output. For larger quantities of cylinders, PyroBus sensors with RS485 Modbus output can be networked in a daisy-chain for direct connection to digital instrumentation.

Application tips
An emissivity setting of 0.95 should give good results due to the high emissivity of painted cylinders. Some plastic wrapping materials are transmissive to infrared at 8-14 microns so the sensor will effectively see through them. For these reasons, the same sensor can be used for painted steel, painted aluminium alloy and composite fibre-wrapped cylinders.

The measured spot size should be no more than half the diameter of the cylinder. A sensor with 15:1 optics positioned at a distance of 200 mm will measure a spot of diameter 25 mm (approx).

Handheld infrared temperature sensors can also be used to determine temperature gradients over the height of the cylinder.