Choose the Right Hardware to Reduce System Cost in Rugged Applications

Rugged applications often include testing in extreme temperature ranges, which can add constraints to hardware. Cold start engine testing, for example, uses a test cell that can drop to -40 °C and requires continuous data acquisition such as temperature, pressure, and other various measurements. Placing hardware that is not built to withstand this range into harsh environments can cause components within the hardware to work incorrectly and result in incorrect data or even damage the hardware.

Figure 1. A test cell is used to perform various tests, including those in extreme temperatures, on engines.

Hardware can withstand these extreme temperature ranges in two ways. The first would be to create an external casing for your hardware to protect it. Depending on which side of the extreme temperature range you are using your hardware in, you may need to implement heating or cooling elements in the enclosure to keep your components at a safe operating temperature. Also, you might consider using shielding and evaluating the color of the enclosure to reflect heat. With all of the considerations for designing an enclosure, it can be an expensive and time-consuming process.

Alternatively, you can select hardware built for withstanding extreme temperature conditions. National Instruments builds hardware to withstand the extreme temperature range by ensuring the components operate properly within these limits. Enclosures are put through extensive thermal tests and validation to ensure the components selected operate within their specifications. This testing also allows the hardware to comply with the international standards for operating within a temperature range.

Another typical consideration when developing a rugged application would be the shock and vibration specifications for your test, and building your setup to withstand it. Applications ranging from monitoring the main gear box of a bucket-wheel excavator power transmission system to taking analog and digital measurements inside of a Formula SAE racecar require consideration of the vibration and shock values that are induced on the testing hardware. If your hardware is placed within a demanding environment where high vibration or shock values occur and cannot handle these values, this could damage your hardware components and cause expensive repair or replacement costs.

Figure 2. This high-vibration application is monitoring the main gear box of the bucket wheel of a KWK-1500s excavator.

When designing a test setup for a rugged environment, there are again a couple of options to compare. You could design an enclosure for vibration and shock to allow the components within the hardware to operate within their given specifications. One approach is to build an enclosure that isolates the hardware from the vibration conditions. . This could be difficult and require a lot of testing to ensure your hardware is operating properly within the vibration or shock conditions.

Alternatively, you could select hardware built to withstand these specifications. NI develops hardware that withstands shock and vibration levels up to 100 g in shock and 10 grms in vibration values when mounted according to hardware documentation. Mounting of NI hardware according to documentation will fully meet international standards and certify the product to its specifications. NI has validated these hardware specifications through extensive testing. 

Figure 3. This vibration test uses the CompactDAQ platform.

Although temperature range and shock and vibration specifications are crucial to address when developing a rugged application, it is also important to consider the environment where you are conducting these tests. This is especially true if this environment is a hazardous location with potentially explosive gas or vapor present during abnormal operating conditions. Examples of hazardous locations include chemical factories or refineries. When developing a test setup for an application in these hazardous locations, it is an important part of the process to have the correct certifications for your setup.

The certifications for operating in hazardous locations, depending on where you are regionally, are the UL Hazardous Locations or the European Union Hazardous Locations certifications. Both certify products for use in hazardous locations where explosive atmospheres may be present. The UL certification comes in a degree of classes and divisions. The classes indicate the type of hazardous location and the division indicates the conditions. The classes offered are from Class 1 to Class 3 with the locations ranging from gas or vapor to dust all the way to dust, fibers, and flyings in a potentially explosive atmosphere, respectively. The divisions are divided into two: Division 1 is for material in normal operating conditions and Division 2 is for material under abnormal conditions.

Typically, you need to run the entire test setup through all of the certification tests to ensure it is compliant to be used in these harsh locations. Testing all of the hardware can be an expensive and intensive process, but is required for operating in these types of environments.

Figure 4. This pipeline test requires a hazardous location certification.

Another certification common for rugged applications is Lloyd’s Register Type Approval. This certification is an assessment by a third party attesting to a product’s conformity with national and international standards, and verification of the manufacturer’s production quality system. Type Approval applies to products for use in marine and offshore applications, industrial plant and processes, and the information technology sector. In addition to ensuring the product meets appropriate safety standards for a marine environment, Type Approval ensures that the product’s performance is maintained in marine environmental conditions.

To obtain this certification, your hardware must go through an entire process laid out by the third party assessing the hardware. First, the third-party group must review all design of the hardware to ensure it complies with specific specifications and codes. Then, they must witness inspection and testing and have those sent in for further review and validation. If everything is approved, then the hardware is validated and authorized to use the Lloyd’s Register Type Approval mark. The hardware certification process is intensive and expensive, which is necessary for your hardware to claim it has this certification.

You may also need protection against solid particle and liquid in the environment. If so, a common certification is the Ingress Protection Marking (IP Rating) which classifies the degree of protection provided against intrusion of dust and water. Most commonly, the IP rating of hardware will have two numbers: the first number indicates the level of protection against solid objects such as dust or moving parts and the second number indicates the level of protection against ingress of water. The first digit ranges from zero to six and the second digit ranges from zero to nine. Each number signifies a different level of protection. As an example, an IP65 rating means the hardware is dust tight and protected against water jet pressure. If a product has a higher second digit IP rating (IP67 for example), it does not guarantee that it is protected against a lower second digit IP rating (IP65 for example). There are different tests to determine water protection rating.  

NI provides a variety of hardware with various industry environmental certifications that comply with the applicable international standards. The hardware has already been put through the rigorous tests that would be needed to certify your application. Certifications range from having your hardware in compliance for use in hazardous locations, having it certified for use in marine environmental conditions and protected against dust and water intrusion. 

When deciding on hardware for a rugged application, the overall form factor is a large consideration. The test system’s footprint is significant when deciding what hardware to use in demanding environments such as on deck an offshore oil rig or in the middle of a desert. If the material the hardware is built out of cannot withstand the harsh environments and needs an enclosure for protection, this could drastically increase the system's footprint. If the enclosure needed to protect the hardware has too large a footprint, this can limit where you can conduct tests. For more distributed and remote applications, you want to minimize the size of the hardware.

Figure 5. Engine test cells are another example of applications that often require rugged hardware with a small footprint.

In addition, consider how the hardware cools itself. Hardware can cool in many ways. The main two ways are passive and active cooling. Hardware that passively cools can be more rugged because there are no moving parts. If your hardware needs moving parts such as fans to cool properly when testing, this could limit where you can conduct tests. With an actively cooled device, there are energy-consuming mechanical components to consider for other rugged considerations such as the temperature range it can operate in or the shock and vibration specifications it can withstand during operation.

Knowing the type of environment your application will be in and how the additional external factors will affect your setup determines whether you want to develop an enclosure for the system or would rather select hardware built for ruggedness.

Deciding on which hardware to use depends on the application. For example, are you monitoring various measurements or performing a control and monitoring application? If you need the flexibility to perform any processing on the built-in FPGA or use it as a controller in a control system, then CompactRIO would be best.

CompactDAQ is a mixed-measurement modular platform with built-in signal conditioning and a large breadth of I/O options. You can create an optimized system exactly for your rugged application without paying for unneeded functionality but with the flexibility to adapt to changing requirements over time. CompactDAQ and all C Series modules are constructed from A380 cast aluminum for a rugged system that can withstand operating temperatures from -20 °C to 55 °C, and up to 30 g of shock. For a more rugged version of CompactDAQ chassis, the cDAQ-9185 and cDAQ-9189 can withstand operating temperatures from -40 °C to 70 °C and up to 50 g of shock. With a rugged, flexible system such as CompactDAQ, you can reconfigure and move a single test system from place to place without having to purchase different equipment for every lab or test stand. The C Series I/O modules, which are used within the CompactDAQ chassis, are equally rugged and designed with spring-loaded latches to lock into place when installed in the chassis. The shock and vibration specifications are all tested on a CompactDAQ system with modules installed, so modules do not fall out or come undocked under the specified conditions. The rugged versions of CompactDAQ systems also have already gone through rigorous testing and come with the UL and European Union Hazardous Locations certifications. The rugged features of CompactDAQ help you quickly begin testing because less time is needed to prepare the instrumentation for the rigors of field testing.

Figure 6. The cDAQ-9189 provides a temperature range of -40 °C to 70 °C, 50 g shock, and 5 g vibration to the  CompactDAQ family, so you can take any measurement, anywhere.

CompactRIO combines an open embedded architecture with small size, extreme ruggedness, and hot-swappable industrial I/O modules and is powered by the LabVIEW reconfigurable I/O (RIO) architecture. Size, weight, and I/O channel density are critical design requirements in many such embedded applications. By taking advantage of the extreme performance and small size of FPGA devices, CompactRIO delivers unprecedented control and acquisition capabilities in a compact, rugged package with extreme industrial certifications and ratings for operation in harsh industrial environments. Temperature ranges of -40 °C to 70 °C (-40 °F to 158 °F), 50 g shock rating, and a variety of international safety, electromagnetic compatibility, and environmental certifications and ratings are all available with CompactRIO.

Figure 7. Ultra rugged CompactRIO systems offer a high level of performance and flexibility.

There are several ways to design and build your system to withstand the external factors affecting your system for applications in rugged and demanding environments. A few of the large topics to investigate include temperature range in the environment, shock and vibration specifications that your hardware needs to withstand, any environmental certifications required, and the type of form factor and features needed for the overall system.

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