Function generator for 4-20 mA drive

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lignux
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Function generator for 4-20 mA drive

Post by lignux »

Hello,

I'd like to generate 4-20 mA waves, that would be connected to a device with a 50 ohms input.
I read that the Pico 5000 series has a 50 ohms output impedance, and +/-2V function generator.

On the paper, it therefore looks perfect.

Could you tell me it this can work, or if the Pico isn't aimed at being used as current generator, and would generate crappy profiles if not connected to an high impedance input ?

Thanks

bennog
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Re: Function generator for 4-20 mA drive

Post by bennog »

4-20 ma sounds like industrial signaling.
If I am correct these units usually have a 600 ohm termination resistor so you need at least 12V to get the 20mA to flow.

Picoscope wont do more than 2V on a unterminated output.

Benno

lignux
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Re: Function generator for 4-20 mA drive

Post by lignux »

After deep diving a bit in the doc, and buying picoscopes, here are my outcomes: some series (e.g. 4000) have a 600 ohms output, so aren't able to inject 20 mA as you said.

But the series 5000 has a 50 ohms output, so it works perfectly.

Thanks

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