SN65HVD35: Maximum nodes for RS-422

Hi David,

If we're purely discussing what the RS-422 standard will allow, this would be correct. However, if we were to use the same hardware for the system and define it as a RS-485 network, this standard would allow 256 nodes. The reason for this is how the two standards define the maximum number of allowable nodes. Where RS-422 states that 10 receivers of a specified input resistance may be used on one bus, the RS-485 standard defines the unit load (U.L.) term based on a different input resistance value and allows 32 of these U.L.s. 

A good depiction of these differences is shown in table 4 of this application report. 

Let me know if you have any questions about this.

Regards,
Eric Schott.