Solution:

USOPTL4 The RS-485 Failsafe Biasing can be changed on the USOPTL4. There is included biasing across the R+, and R- lines. The included biasing resistors R20,( pull up) and R22 ( pull down) are 4.7K ohm surface mount resistors. Through hole location R3 is in parallel with R20, and location R1 is in parallel with R22. The resistors R20, and R22 can be removed, or left in place, depending on the overall resistance value that you want to use. Resistors would be soldered into locations R3 and R1 to change the Biasing Value. The resistor location, R16 is a location for an optional termination resistor. Effects USPTL4, USPTL4-LS, USOPTL4, USOPTL4-LS