Solution:

4WSD9OTB The RS-485 RECEIVE Failsafe Biasing can be changed on the 4WSD9OTB and 4WSD25OTB. There is included biasing across the R+, and R- lines as well as the T+ and T- data lines. The included RECEIVE biasing resistors R2, ( pull up) and R10 ( pull down) are 4.7K ohm surface mount resistors. The included TRANSMIT bias resistors R3 ( pull up ), and R11 ( pull down) are 4.7K ohm surface mount resistors. For RECEIVE biasing, through hole location R1 is in parallel with R2, and location R9 is in parallel with R10. The resistors R2, and R10 can be removed, or left in place, depending on the overall resistance value that you want to use. Resistors would be soldered into locations R9 and R1 to change the RECEIVE Biasing Value. TRANSMIT biasing does not have through hole locations for changing the biasing value. The resistor location, R7 is a location for an optional termination resistor. Effects 4WSD9OTB and 4WSD25OTB