I intend to use ISO15 RS485 transceiver for my application. I want to know how to decide upon the suitable value of pull-up and pull-down resistors on the REn and DE pins, if I intend to have jumpers installed in case I want to enable/disable the communication. Also, please tell me how to decide upon the cut-off frequency of the RC filters between the Rx, Tx pins of microcontroller and the corresponding pins of the ISO15 chip. An illustration is given in www.ti.com/.../slla299.pdf.