Yacht Devices YDNB-07N, User Manual, Page: 18 / 46

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NMEA 2000 Standard does not require a strict order of fast-packet frames on the bus. Device CAN controller
has 3 "outboxes", thus fast-packet CAN frames can be put in different "outboxes" in the outgoing queue, this
may lead to fast-packet frames to be sent out-of-order. Some NMEA 2000 equipment can not handle this
situation well, in such cases use the following data flow control setting:
STRICT_QUEUE=OFF|CAN1|CAN2|ON
This setting forces strict order of outgoing fast-packet frames for CAN1, CAN2 or both interfaces (ON). By
default is disabled (OFF). Enabling has a slight performance penalty.
3. Hardware filters
CAN1_HARDWARE_FILTER_y=f,m
CAN2_HARDWARE_FILTER_y=f,m
y — number of the hardware filter, decimal number from 1 to 7;
f — filter value, decimal or hexadecimal number (29 significant bits);
m — filter mask, decimal or hexadecimal number (29 significant bits).
The Device can filter messages received from the CAN1 and CAN2 interface at hardware level, which in
some cases can reduce the load on the microprocessor by a factor of up to a 100. The message selection is
carried out through the 29-bit identifier of CAN frame (CAN ID), which contains the message priority, PGN,
the sender’s address and (in some cases) the recipient’s address.
Formal match comparison expression for both hardware and software filters is:
if ( ( CAN_FRAME_ID AND mask ) == filter ) then MATCH else NO_MATCH
Messages are only passed to the program if they match one of the hardware filters. It is possible
to set up to 7 custom hardware filters for each interface, with numbers from 1 to 7.
Device also has a system hardware filter number 0 which can not be modified by user:
CAN1_HARDWARE_FILTER_0=0x00E80000, 0x01F90000
CAN2_HARDWARE_FILTER_0=0x00E80000, 0x01F90000