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AM26C31: Reasons for being classified as half duplex

Shinichi Inoue
Guru 21811 points
Part Number: AM26C31
Other Parts Discussed in Thread: AM26C32

Dear Specialists,

My customer is interested in AM26C31 and AM26C32.

They have a question about description of RS-485 & RS-422 transceivers chart.

I would be grateful if you could advise.

---

According to the product folder, AM26C31 and AM26C32 are categorized to half duplex.

Generally speaking, duplex half is a process in which a pair of  cables are shared and the transmission and receive are time-split.

AM26C31 and AM26C32 have separate transmit and receive lines, so I don't think they are duplex half.

Please give me the definition of duplex half.

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I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    Guru 318050 points

    A duplex system allows communication in both directions, i.e., "duplex" applies only to transceivers. The AM26C31 and AM26C32 are not duplex but simplex, and therefore, "full duplex" or "half duplex" do not make sense. (You would need to combine multiple 31/32 devices to get full duplex.)

    That column is labelled "duplex", so for the AM26C31 and AM26C32, it should be empty or "N/A". The "half" value is wrong; just ignore it, and use the number of receivers/transmitters to search.

  • +1
    TI__Guru 52692 points

    Hi Shinichi,

    Yes these parts should have N/A or blank for the duplex because these are only drivers or only receivers - and not both. Since they are in our RS-485/RS-422 group of devices the duplex category is there and it must have been auto-filled on accident.

    So Clemens analysis is also correct. 

    Best,

    Parker Dodson

  • 0 in reply to Clemens Ladisch
    Guru 21811 points

    Hi Clemens,

    Thank you for your reply.

    My client had the same understanding as you about duplex

    They did not understand why AM26C31 and AM26C32 are classified as half duplex.

    Your comment showed us that it was a mistake.

    I'll share with the customer.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    Guru 21811 points

    Hi Parker,

    Thank you for your reply.

    I understand the devices may wrongly auto-filed.

    Some other devices are incorrectly listed as half duplex as well.

    I hope they will be corrected to prevent confusion.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi