SN65HVD1791 Fault-Protected RS-485 Transceiver (datasheet SLLS872I –JANUARY 2008–REVISED AUGUST 2015):
On the datasheet page 22, it says "Use 1-kΩ-to-10-kΩ pullup and pulldown resistors for enable lines to limit noise currents in these lines during transient events".
In one of our designs such resistors were not used, and we face issues indicating that the RS-422 device in the other end needs to be driven, even when not sending data. Thus it seems to not be according to the Idle bus conditions that occur when no driver on the bus is actively driving the lines.
Could the lack of such resistors explain what is described above?