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PGA300: Requirements of OWI communication between EVM and PGA300

Part Number: PGA300

Hello,

I would like to know following requirements of OWI communication.

1) Cable length

2) Cable thickness

3) Baud rate

4) Loop resistance (Termination resistance)

I think Baud rate is decided after recomendation cable length, type (line resistance), but I don't know these recomendation requirements. Could you teach me that?

Regards,

  • Hello,

    The main concerns for the OWI communication will be the line resistance and capacitance. Especially if you are using 4-20mA output mode, the total loop resistance will be affected by the resistance of your cabling. I recommend keeping the total loop resistance under 100ohm, The capacitance of the line will also play a role.

    The capacitance between VDD/OWI and GND should be between 10nF and 100nF. I would recommend closer to 10nF if you intend to use higher baud rates. The highest baud rate that is recommended in the datasheet is 9600bps.

    So as a general recommendation, keep the baud rate to 9600bps or lower, the total loop resistance below 100ohm, and the total capacitance below 100nF, but preferably close to 10-20nF.


    Regards,

  • Hello,

    I'll prepare OWI communication such as contents of attached file. Could you confirm these condition? If these conditions have some problems, could you tell me recomended condtion?

    Condition of OWI communication.pptx

    Regards,

  • Hello,

    Based on those cable specifications the OWI communication should work over that distance. My only concern would be if there are other signals bundled in the same cable that could couple onto the OWI lines. If you only have DC lines then it should be no problem.

    Regards,