Consider a RS422/RS485 receiver like the AM26LV32 or the DS26LV32. It is used to receive the signal of incremental encoders with differential outputs. Assume that those are using drivers such as the AM26LV31. There is only receiver on the bus, i.e., driver and receiver are at opposite ends of the cable.
Seemingly to facilitate the use of encoders without differential outputs, the schematic omits the termination typical for RS422/RS485. On the receiver side, there is no resistors between the positive and negative line of the differential pairs. Instead, the schematic has a 1kOhm pulldown and a 2kOhm pullup (to 5V) on both the positive and the negative line of each differential pair.
Datasheets typically recommend a termination resistor (200 Ohms or so) between the positive and the negative line of each differential pair. As far as I understand, that helps with reflections. Now this schematic omits it.
What will be the consequences of omitting the termination? What issues are likely to occur when attaching encoders which may reach switching rates as high as 30 MHz? You may assume that these encoders have differential outputs.