Once you have deployed your PXI system, it is important that you use and maintain it properly. If you are not be the only operator of the system, you should educate the other operators on proper use and maintenance of the system. Failure to do so can lead to easily avoidable measurement errors or downtime.
Using your PXI system properly begins with implementing a software architecture that eliminates unnecessary access to hardware that can artificially reduce operating lifetime. One example is designing your application so that data is written to and read from the hard drive only when necessary. In a data-logging application, it may make sense to buffer multiple data points in an array in memory and write them to a file on the hard drive when the buffer is full as opposed to writing each point to the file immediately after it is acquired.
Software Recovery and Backup
Many problems that appear to point to hardware failure are actually associated with software. For example, after deployment, you could install a piece of software (application, driver, and so on) on your PXI system that has a conflict with the driver for one of your PXI modules. Because this module has functioned properly in the past, and you have made no changes to your system directly associated with this module, you could reason that the module is malfunctioning. Another example is your PXI controller being infected by a virus. If the virus caused your controller to randomly crash, and you were not aware of the virus, it would seem that your controller is malfunctioning.
It is important to verify that you are not facing a software problem before deciding that your hardware has malfunctioned and returning it to NI to be repaired. If you determine that your PXI system has a software problem, being able to take advantage of recovery software can significantly reduce downtime. All NI Windows-based embedded controllers include hard drive-based recovery images and software. When you receive the embedded controller from the factory, it has a separate partition on the hard drive that includes a complete back-up image. You can re-image your embedded controller back to the factory image at any time without needing a CD, secondary hard drive, network connection, and so on. Moreover, you initiate the recovery process during boot before Windows has loaded, so even if your embedded controller cannot boot into Windows you can still recover the factory image.
The recovery software that is included on NI embedded controllers also gives you the ability to create custom backup images that can be stored on external or secondary hard drives, such as USB drives, and used as the recovery image instead of the factory image. After your PXI system is completely assembled and tested, you could create a custom backup image that you can use for recovery if you experience software problems after deployment.
Figure 10. With recovery software, you can restore you PXI systems to a known-good state and reduce downtime.
System Power Down
If your PXI system uses a general-purpose operating system, such as Microsoft Windows, it is important that you follow the proper power down procedure. With a PXI chassis, such as the NI PXI-1045, after you have instructed the operating system to shut down, you receive a message on your monitor informing you that “It is now safe to shut down your computer.” At this point, you can power down your system using the chassis power switch. With a PXI Express chassis such as the NI PXIe-1062Q, the chassis automatically powers down by default after instructing the operating system to shut down. If you do not follow the proper power down procedure for your system, your controller’s hard drive experiences avoidable wear.
Cleaning Chassis Fan Filters
You must clean the chassis fan filters located at the air intake at a maximum interval of six months. Depending on the amount of use and ambient dust levels in the operating environment, the filters may require more frequent cleaning. A good practice is to clean the filters whenever they become visibly dirty. Dirty fan filters can dramatically reduce the cooling performance of your chassis. The NI manufacturing facility in Austin, Texas experienced an 8 to 10 °C reduction in internal temperatures within certain chassis used for functional test after implementing a schedule for cleaning the fan filters. Refer to your chassis operating manual for cleaning instructions. If desired, you can replace the fan filters. Refer to your chassis operating manual for ordering information.
Figure 11. Chassis fan filters located at the air intake must be cleaned at a maximum interval of six months.
Cleaning Other System Components
Periodic cleaning of your entire PXI system increases reliability, especially if it is deployed in a dusty environment. Refer to the operating manuals for your chassis, controller, and modules for complete external and internal cleaning instructions.
Monitoring System Conditions
System conditions can change over time. The most common example of this is the ambient temperature of your PXI system rising. Many factors can cause this change in ambient temperature – for example, adding new equipment to the rack where your PXI system is deployed. Regardless, it is a good practice to periodically monitor the ambient temperature of your PXI system. Many of NI embedded controllers have internal temperature sensors that can be monitored programmatically. The example program Measuring the Temperature of Your PXI Embedded Controller demonstrates this. However, since the ambient temperature of your PXI system is measured at the chassis air intake, the measurement of the controller temperature is for reference only. You can do this manually or automate it by integrating the measurement into your PXI system.
Another system condition that can change over time is the health of your controller’s hard drive. It is good practice to periodically monitor the health of the hard drive with hard drive diagnostic software. NI provides a hard drive diagnostic tool for use with PXI and PXI Express embedded controllers.
The accuracy of the electronic components used in all instruments drift some amount over time. The effects of time in service as well as environmental conditions add to this drift. As time progresses, changes in component values cause calibrationgreater uncertainty in your measurements. To resolve this issue, the instruments in your PXI system must be calibrated at regular intervals. Maintaining properly calibrated instruments reduces measurement errors, improves consistency between measurements, and provides you assurance that you are making accurate measurements.
Figure 12. Calibrating instruments resolves inaccuracies that accumulate over time.
External calibration is the comparison of instrument performance to a standard of known accuracy. The result of an external calibration may be documentation showing the deviation of a measurement from the known standard, but most often it also includes adjusting the measurement capability of the instrument to ensure that its measurement accuracy is within vendor-provided limits. To have your PXI instruments from NI externally calibrated, you can send them back to NI, send them to a calibration or metrology laboratory, or use the external calibration capabilities at your facility (if available). Complete calibration resources are available on the Calibration Solutions from NI page.
In addition to external calibration, many PXI instruments from NI include self-calibration functionality. Instruments that offer self-calibration include hardware resources such as precision voltage references so you can quickly calibrate the instrument without removing it from the chassis or connecting it to external calibration hardware. Self-calibration is not a replacement for external calibration, but it does provide a method of improving instrument measurement accuracy between external calibration intervals.
Integrated Troubleshooting Resources
PXI products from NI include numerous integrated features that aid in troubleshooting. For example, most modules include the ability to perform an automated self test of the module’s functionality. Many of the chassis also include a power switch with an integrated LED that visually indicates the operating condition of the chassis. The four states are the following.
- If the power switch LED is steady green (not flashing), the chassis is powered on and operating normally.
- If the power switch LED is flashing green, the air-intake temperature has exceeded the chassis operating range.
- If the power switch LED is flashing red, the power supply outputs are not within voltage regulation requirements.
- If the power switch LED is steady red, the chassis fans are not operating properly.
Many PXI system problems are misdiagnosed as faulty hard drives when the actual problem is due to software, file corruption, file system corruption, or a virus. Many hard drive vendors provide hard drive diagnostic tools that determine if an actual hard drive failure has occurred. These tools can save you costly troubleshooting time and should be used before returning the hard drive, PC, or controller repair. NI provides a hard drive diagnostic tool for use with PXI and PXI Express embedded controllers. If you use a hard drive diagnostic tool to determine that your hard drive has not failed, then you most likely can take advantage of recovery software to fix the issue.
Stocking Spare Components
If you determine that a component in your PXI system needs to be returned to NI for repair, you can significantly reduce the downtime of your system by stocking spare components at the location where the system is deployed. You can choose to stock a replacement for every component of your system (chassis, controller, modules, and so on). If you are deploying multiple identical PXI systems, and plan to stock spare components, NI recommends that you stock one spare of each component used in the systems for every 25 systems that you are deploying.
You can also decide to only stock subcomponents that have a higher likelihood of failing. NI supports you in this strategy by offering replacement chassis power supply shuttles and embedded controller hard drives. These kits include detailed documentation that explains how to replace these subcomponents in the field.
Figure 13. One spare strategy is to stock subcomponents that have a higher likelihood of failing, such as hard drives.
The strategy that you employ for stocking spare components should be dictated by the amount of downtime that you can accept. Regardless of the strategy that you choose, NI works to decrease the downtime of your PXI system by minimizing repair times for products that you return for repair, providing expedited repairs, and stocking replacements products around the world so that they can be delivered to you as quickly as possible.
Worldwide Technical Support
If you do need assistance troubleshooting an issue associate with your PXI system, NI has local staff in offices around the world. You have access to NI field engineers who speak your language and are available to help you get your system back online as quickly as possible. NI also has an award-winning, worldwide support organization staffed with applications engineers trained to quickly provide superior technical assistance via phone, e-mail, or Web.