Hi There,
I would like to get some recommendations on a new design I am working on. I have never interfaced these current loops and just want to make sure I am going about this in the most efficient manner. I have the task to create a control board will run a control loop from a 4-20mA sensor to a DSPIC controller and outputs a 4-20mA current loop to control a proportional valve. The system needs to be able to interface on a RS-485 bus.
I have found that there are some pretty nice ICs that contain most of the circuitry to A/D and D/A the current loops. I have found some interface chips that seem like they will do the job for what I need. I am hoping to get some feedback for whether these will indeed most efficiently do the job for what I need, or if not I would hope to get some feedback to get me on track.
Here are the parts that I am thinking of using:
4-20mA current loop A/D: AD7707
4-20mA current loop D/A: AD421
RS-485 2 wire transceiver: SN65HVD1782D ( not available through element 14) Hopefully you can recommend a part from here that will work.
Controller: PIC33F micro
Thanks for any insight you may have for me.
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