Why Does my [c]FP-DO-400/401 Have Channels Stuck in the On Position? Hardware: FieldPoint>>Discrete I/O Modules>>FP-DO-400, FieldPoint>>Discrete I/O Modules>>FP-DO-401, Compact FieldPoint>>Discrete I/O Modules>>cFP-DO-400, Compact FieldPoint>>Discrete I/O Modules>>cFP-DO-401
Problem: My [c]FP-DO-400/401 has channels stuck in the ON position, but the LED functions 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 be damaged by a noisy power supply. (Note: Sometimes power supplies will spike when they are plugged in, and this may damage the module.) When a channel of the [c]FP-DO-400/401 is damaged, the channel will remain in the ON position. Though the LED will turn on and off correctly, the module will always output a high voltage. To prevent against this type of failure, you will need to attach a properly selected transient voltage surge suppressor (TVSS) between V and C. Once the module is damaged, it will need to be returned 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, and then other end to the C terminal on the terminal block. Note: Please note that 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 supply and need assistance selecting the appropriate TVSS, please contact your applications engineering department. Related Links: Attachments:
Report Date: 12/03/2007 Last Updated: 03/03/2008 Document ID: 4G2EC3K8 |
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