C Series Mounting Guidelines

CompactRIO, CompactDAQ, and MXI-Express RIO platforms are designed and tested in several mounting configurations over the rated ambient temperature ranges.  The varied mounting orientations or configurations can reduce the maximum allowable ambient temperature and can affect the typical accuracy of C Series IO modules in the specific platforms.  The tables below detail the maximum allowable ambient temperature ranges for operation and the impact on the ability to achieve C Series typical specifications.

Refer to your device's specifications document to determine which temperature column is appropriate for your device. 

Note: Some CompactRIO, CompactDAQ, and MXI-Express RIO systems have additional restrictions or other important information regarding thermal performance. Refer to your system user manual or operating instructions for this information. 

For information about mounting options for your C Series hardware, refer to either the CompactDAQ Controller & Chassis Mounting Accessories or the CompactRIO Mounting Options & Enclosures pages of NI's Cable and Accessory Guide.

For mounting requirements and thermal specifications for the cDAQ-9138/9139 controller products, refer to the Tutorial NI CompactDAQ Controller Mounting and the Impact on Measurement Accuracy

For reference, Figure 1 below shows a MXI-Express RIO chassis mounted horizontally with an NI Panel Mount kit.  Figure 2 below shows a 1-Slot cDAQ sleeve mounted horizontally.

Figure 1:  NI 9157/9159 Mounted Horizontally.

Figure 2:  NI 9181 Mounted Horizontally.

C Series modules are designed to provide high-accuracy measurements.  From the factory, most analog I/O modules are calibrated against a NIST-traceable precision source.  Accuracy is guaranteed for at least one year after calibration and each module can be re-calibrated through-out its life.   While C Series system components can safely be used together across the rated temperature range, analog module accuracy is sensitive to heat. 

For all measurement systems, proper wiring, noise shielding, and grounding practices are essential to achieving high accuracy analog measurements.  Assuring proper connectivity and wiring should be the first step when designing a high accuracy measurement system.  To assist in designing your system we recommend visiting the Measurement Fundamentals White Paper article.

Calculations for C Series maximum accuracy specifications assumes a worst case range of component tolerances and a full thermal load on the system (maximum processor and FPGA usage, and a chassis fully loaded with high power modules). Many C Series analog modules also provide specifications for typical accuracy.  Because most systems are not subjected to such high thermal loads and extreme component tolerance, NI also provides typical accuracies, in addition to maximum accuracies, to help guide you on the accuracy that can be expected from common configurations.  While typical specifications are not guaranteed, most systems mounted and oriented in accordance with the guidelines above will meet the published typical specifications.  C Series systems not adhering to the guidelines may also meet the published typical specifications, but are significantly less likely to do so.

You can increase analog module accuracy by loading the modules into your CompactRIO, CompactDAQ, or MXI-Express RIO chassis in an arrangement that separates analog modules from high-power-dissipating modules such as digital output, communications, or motion modules and from other thermally significant system components such as external power supplies, relays, -etc.  The maximum power dissipation for each module is specified in the module data sheet.  We recommend loading high-power modules and all digital modules starting with slot 1 on the left side of the chassis, and your analog modules starting on the right side of the chassis.  This will minimize the temperature rise in the analog modules and provide increased accuracy. Additionally, installations must meet the requirements for space and cabling clearance as defined in the operating instructions provide with the chassis in use. 

• Product Documentation: Ensuring Measurement Accuracy in High-Power CompactRIO Systems (cRIO-9081/2)