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Using LabView to controll a Heat Exchanger

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I believe i've made a correct working program in LabView to control a heat exchanger but have been unsuccessful running the machine in remote mode. I'm sending a 24V signal from a power supply through a NI 9482 electromechanical relay and can't seem to get it to turn on. I'm measuring the correct voltages to the correct pins at the equipment plug but nothing happens when I turn them on and off. Does anyone have an idea of what could be going on?

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Message 1 of 7

Hi swanholm,


does your "SMC" device work when you connect pins 3 (and/or 4&5) to pin 9 with a wire? Did you supply 24V to pin 10?

Did you check correct voltage levels at those pins when contacting your relay?


Your VI images are useless as they hide all relevant information in thos eExpressVIs. We also cannot check your (hardware) wiring…

Best regards,

using LV2016/2019/2020 on Win8.1/10+cRIO
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Message 2 of 7

Yes I measure the correct voltages between whatever control i turn on and pin 9 (common). So i turn on the pump control in my vi and i measure 24V between pin 5 and 9

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Message 3 of 7

I also measure 24V from pin 10 to 9

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Message 4 of 7
Accepted by topic author c-swanholm

Hi swanholm,


pins 3-5 should be connected to COMMON aka GND according to your sketch!


(Do you notice those small photodiodes in the sketch behind pins 3-5? What will happen when you supply 24V at the cathode of these diodes while the anode is also connected to +24V?)

Best regards,

using LV2016/2019/2020 on Win8.1/10+cRIO
Message 5 of 7

omg... yep thanks... Ill try that

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Message 6 of 7

worked like a charm thanks for catching that i deffinitely missed it with those wires crossing in the schematic

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Message 7 of 7