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THVD1451: Multi-point or Multi-drop bus topology

Koshi Ninomiya
Expert 4105 points
Part Number: THVD1451

Dear Team,

My customer is thinking to use the THVD1451 Full-Duplex None-Enables RS-485 transceiver in their system. Since the THVD1451 does not have Enables, Bus topology will be Multi-drop, right?
One Master and multi Slaves.

The Bus line from the Master (Driver) to multi Salves (Receiver);
It is OK for multi Slaves to be powered on, because multi Slaves are receivers.

The Bus line from multi Slaves (Driver) to the Master (Receiver);
When one Slave drives the Bus to transmit the data to the Master, the other Slaves should be powered off not to drive the bus, right?
How to control the timing of power-on of Slaves?

I look forward to your reply.
Thank you.

Best Regards,

Koshi Ninomiya

  • +1
    Guru 243980 points

    The most basic application of the THVD1451 is a connection between exactly two devices, where both are always active.

    If there are multiple transmitters on the same line, then all of them must have the ability to be disabled.

    In your example, all slaves must use a transceiver with enable pins, and you must use a protocol that specifies when a slave is allowed to send (e.g., a command-response protocol, where only the master sends commands).