I connected the ARK Flow sensor to PX4 of my PX4Vision on the CAN1 port and set the UAVCAN parameter as suggested in the online guide. According to the guide this is the only setting in order to have the sensor work. I disconnected the PIX4Vision optical flow sensor and rangfinder (TELEMETRY 3 Port and GPS2 Port). The problem is that the ARK Flow sensor does not communicate because I do not see the related topic in MAVLINK Inspector.
thanks a lot for your reply. The LED is fixed Blue.
Now the sensor is working. I did not set UAVCAN_SUB_FLOW and UAVCAN_SUB_RGN because in an old PX4 guide that I consulted they were not indicated. Then I find a new one in which they were indicated. In addition I find that all the other SENS parameters related to optical flow sensor has to be disabled.