We are using TI RS485 drivers to implement a local half-duplex RS485 communication bus between adjacent boards. Unfortunately, at ~50C, the RS485 interface stops communicating. At first we thought the absence of termination might be driving it, so we added a 60 ohm resistor (its a local bus with no distinctive end-end distance, so this in lieu of two 120 ohm termination resistors). This did not make a difference. We also removed the TVS diodes shown, and replaced the series termination resistors with shorts, and it still shuts down at around 50C. Any idea what is happening to the RS485 interface? Do you agree that for a local bus only a few inches long, then no termination is required? Do I need to add bias resistors to power and ground too with the termination? Please Help? Thanks.