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# SN65HVD01:communication distance according to the voltage supplied to the Transceiver.

Part Number: SN65HVD01

I want to know the communication distance according to the voltage supplied to the Transceiver.

Is there a difference in communication distance between 3.3v and 5v?

What is the maximum communication distance when the supply voltage is 3.3v?

- If the communication distance is far, the voltage drops, is there a difference between 3.3v and 5v?

• #RS485

Is there a graph of supply voltage and communication distance?

• Won,

We'll take a look at this and get back to you tomorrow. I can tell you for a fact we don't have a graph of supply voltage and communication distance, and there isn't a straightforward answer for that question. It is system dependent.

Regards,

Eric Hackett

• As I know it,
I understand that the longer the cable length, the more voltage drops occur.
Is there any information about the maximum distance when the supply voltage is 3.3v?

If such information is not provided, can I make the cable long as I want?

• Won,

No, RS-485 has a distance limitation based on data rate in the specification. As a percentage, the voltage drop across cable is the same for 5V and 3.3V, but since 5V is higher from an absolute perspective, you're going to have more margin and thus a longer cable ultimate. The supply voltage however, is not the only determining factor when it comes to cable distance. Timing due to other components on the bus AND cable will affect the distance based on what data rate is used.

I will look to see if I can find more specific test data or documentation on this.

Regards,

Eric Hackett

• Are you that 5v is better than 3.3v in the same environment(data rate)?

please check if there is a document related to the power supply and cable length.

• Won,

It's more dependent on the VOD of the transceivers and not the supply voltage. So if the 3.3V and 5V RS-485 transceivers have the same output differential voltage, their communication distance will be similar.

Regards,

Eric Hackett

• I wanted to know the length of the cable that changes depending on the power supply.

Thank you :)

• Won,