Cyclone V HPS - CAN TXD and RXD connection

I try to get the CAN two pins (CAN_RXD and CAN_TXD) to be tested at the Cyclone V pins. I use the CAN test register (CTR) to read CAN_RXD and to toggle CAN_TXD, however I observe no change. Has anybody done that before and can guide me to the necessary steps?

Thanks!