AXIOMATIC UMAX030440 User Manual Download Page 16

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UMAX030440 Version 2B 16-51

The CAN Transmit messages can be sent on any Proprietary A or B PGN as broadcast messages.
By default, the

Message Priority

is set to 6 (low priority).

The

Destination Address

of the J1939

Identifier can be changed to any value between 0…255.

The

Data Size

Data Index in Array (LSB)

Bit Index in Byte (LSB), Resolution

and

Offset

can

all be used to map any SPN supported message by the J1939 standard from any

Data

Source/Number

of the Transmit Function Block.

Note: In this case, when the Data Size is set to 32 bits for all 4 control sources, each next value
will erase the previous data in a CAN Transmit message at the place where they are overlapping.

1.13. CAN Receive Function Block

The ECU supports up to 10 unique fully configurable CAN Receive Messages. The CAN Receive
function block is designed to take any SPN from the J1939 network and use it as a

Control

Source

for any relay outputs or CAN transmits.

The

Receive Message Enabled

is the most important setpoint associated with this function block

and it should be selected first. Changing it will result in other setpoints being enabled/disabled as
appropriate. By default, all receive messages are disabled.

Once a message has been enabled, a Lost Communication fault will be flagged if that message is
not received within the

Receive Message Timeout

period if this has been set to 10ms or higher.

This will trigger a Lost Communication event and the output data of the CAN Receive message will
be set to 0. To avoid timeouts (if set to 10ms or higher) on a heavily saturated network, it is
recommended to set the period at least three times longer than the expected update rate. To
disable the timeout feature, simply set this value to zero, in which case the received message will
never timeout and will never trigger a Lost Communication event.

By default, all control messages are expected to be sent to the ECU on Proprietary B PGNs.
However, should a PDU1 message be selected, the ECU can be configured to receive it from any
ECU by setting the

Specific Address that sends the PGN

to the Global Address (0xFF). If a

specific address is selected instead, then any other ECU data on the PGN will be ignored.

The

Data Size

Data Index in Array (LSB)

Bit Index in Byte (LSB)

Resolution

and

Offset

can

all be used to map any SPN supported by the J1939 standard to the output data of the Received
function block.

The

Data Min

(Off Threshold) and

Data Max

(On Threshold) setpoints determine the minimum and

maximum values of the control signal. As the names imply, they are also used as the ON/OFF
thresholds for digital level types. These values are in whatever units the incoming data is

after

the

resolution and offset are applied to the CAN Receive signal.

To have a CAN Receive message trigger, a relay output ON or OFF is to make sure the

Data Min

(OFF Threshold)

and

Data Max (ON Threshold)

parameters are adjusted to the user’s

application. When the CAN Receive message (after having the resolution and offset applied to it),
anything at

Data Max (ON Threshold)

parameter or higher, will trigger an ON command. Similarly,