Why Does my [c]FP-DO-400/401 Have Channels Stuck in the On Position?Hardware: PXI/CompactPCI>>Controllers
Problem: My [c]FP-DO-400/401 has channels stuck in the ON position, but the LEDs function properly. The module only outputs a high voltage. What happened? How can I avoid this in the future? Solution: The [c]FP-DO-400/401 module may have been damaged by a noisy power supply. When a channel of the [c]FP-DO-400/401 is damaged, the channel will remain in the ON position. Though the LEDs will turn on and off correctly, the module will always output a HIGH voltage. To prevent against this type of failure in the future, you need to place a properly selected transient voltage surge suppressor (TVSS) between V and C of the module. Refer to page 11 of the [c]FP-DO-401 manual for this caution. Modules released since August 2008 have the TVSS included. If a module has already been exposed to transient voltages, attaching a TVSS may not prevent the error as damage may have already occurred. If this is the case, you will need to return your module to National Instruments for repair. If you are using a 24V supply, you can use one of the following TVSSs: Littlefuse ST Micro Vishay To hook the TVSS up to the [c]FP-DO-400/401, connect the side of the TVSS with the line/bar to the V terminal on the terminal block. Then, connect the other end to the C terminal. If using a cable instead of a terminal block, V &C can be accessed as follows: V is pins is 33 and 34, and C is pins 35 and 36 . It is recommended that you connect each V to V and each C to C as well, since they are not wired internally in the backplane. More information about the cable pinouts can be found here: KnowledgeBase 2S49EPOH: Pin Assignments for Compact FieldPoint and Compact RIO Custom Cables Note: The TVSSs listed above are only going to be effective for use with a 24V or lower rated power supply. If you are using something above a 24V supply, the power supply voltage will be clamped. If you are not using a 24V power supply and need assistance selecting the appropriate TVSS, please contact your applications engineering department. Related Links: Product Manuals: FP-DO-401 and cFP-DO-401 Operating Instructions KnowledgeBase 2S49EPOH: Pin Assignments for Compact FieldPoint and Compact RIO Custom Cables Attachments:
Report Date: 12/03/2007 Last Updated: 05/05/2009 Document ID: 4G2EC3K8 |
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