Unexpected Relay Behavior on [c]FP-RLY-42x Modules Hardware: Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-420, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-421, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-422, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-423, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-425, FieldPoint>>Discrete I/O Modules>>FP-RLY-420, FieldPoint>>Discrete I/O Modules>>FP-RLY-422, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-420, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-421, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-422, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-423, Compact FieldPoint>>Discrete I/O Modules>>cFP-RLY-425
Problem: When I write to one or more channels on a [c]FP-RLY-42x module, other channels on that module or adjacent modules exhibit unexpected behavior. Why is that? Solution: National Instruments recently discovered that if NI [c]FP-RLY-42x FieldPoint or Compact FieldPoint relay modules are exposed to high levels of electromagnetic interference (EMI), relays in the modules or in adjacent modules may open or close unexpectedly. The unexpected relay closure issue was discovered during internal testing and is unlikely in most use cases. National Instruments is expediting upgrades to these products to make them more immune to high levels of EMI. Additional information on how to reserve an upgraded module is included below. Sources of EMI include noise from switching inductive loads (for example, motors and solenoids) and power-supply surges. Proper customer-installed surge suppression on the power supply, and the use of metal oxide varistors (MOVs) or flyback diodes across the load, reduce the effects of EMI and make unexpected relay behavior less likely. Please refer to the operating instructions for your [c]FP-RLY-42x for more information about properly connecting MOVs and flyback diodes. The following link has additional information regarding protecting your relay module when switching inductive loads: KnowledgeBase 4IHG8JLE: Protecting NI Switch Modules when Switching Inductive Loads In addition to unexpected relay closures, high levels of EMI may also cause a [c]FP-RLY-42x to reset unexpectedly. When the module resets, all channels open for 100 ms before returning to the position they were in. You may notice a momentary dimming of the Ready light on the module, or an unconfigured channel error in Measurement & Automation Explorer (MAX), LabVIEW, or other programming environment you are using. Also, the cFP-RLY-425 may report false over temperature errors in MAX, LabVIEW, or another programming environment. This error causes all eight channels to remain in the open position until the module is reset either by hot swapping the module or by rebooting the controller. ACTION REQUIRED – Evaluate the use of these products in your application to ensure that unintentional opening and closing of relays will not create a hazard. Until the new designs are available, we recommend using a [c]FP-DO-410 to drive external relays in place of a [c]FP-RLY-42x. If the [c]FP-DO-410 driving external relays is an acceptable solution for your application and you want to replace your [c]FP-RLY-42x modules with [c]FP-DO-410 modules, please call National Instruments at (800) 206-8107 to obtain a service request number and to arrange shipping. Please note that if you choose to replace a [c]FP-RLY-42x with a [c]FP-DO-410 and external relays, you must modify your code to work correctly with the new module. You must update your .iak file to include the new module, and you must ensure that all FieldPoint I/O controls and constants that previously referred to channels of the [c]FP-RLY-42x now refer to the correct channels of the [c]FP-DO-410. If you need help doing this, please contact the Applications Engineering department of National Instruments by calling (800) 206-8107 and ask to speak with a technical representative. Below is a table of recommended external relays from Phoenix Contact that you can use with the [c]FP-DO-410 to replace the different [c]FP-RLY-42x modules. The table contains links to the corresponding product pages of the different Phoenix Contact relays. Table 1. Recommended External Relays
Wiring Instructions for [c]FP-DO-410 with External Relays (DEK-REL-24/1/AKT)
Wiring Instructions for [c]FP-DO-410 with External Relays (EMG10-REL/KSR-24/21-LC)
Related Links: KnowledgeBase 4IHG8JLE: Protecting NI Switch Modules when Switching Inductive Loads Attachments:
Report Date: 01/04/2008 Last Updated: 03/03/2008 Document ID: 4H3DG7SK |
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