Version 2.0.3 Preliminary Documentation – May be Subject to Change 14-36
Example 4: Output Feedback Message
A –5 to 5V output channel is configured to periodically send the feedback message to the network.
The data will be sent to the bus using PGN 65283 and for this output type it has a resolution of
1mV/bit with a -5000mV offset. The controller has the output set to –2.74V, and the message sent
to the bus is as shown, with 2260mV as the data.
29 Bit ID
#bytes
ID Status Value
18FF0380 8
0F 01 D4 08
FF FF FF FF
2.2.
Multiple Channel Messages
For any Proprietary B PGN that is used to send data associated with more than one channel, the
format of the data in the message will be as described below.
The same will apply for all other
PGNs shared by multiple channels.
The Repetition Rate of the message that will be sent to the bus will be the one from the LOWEST
index channel. This means that if this channel has the repetition set to zero, the message will NOT
be sent to the bus, even if other higher number channels with the same Transmit PGN have a non-
zero repetition rate.
Each channel will use its own resolution and offset for the data.
WARNING: If more than one channel sharing a PGN has the same data index into the
array, the data from the HIGHEST channel will be sent. This problem will also be
present if a 2 or 4 byte setpoint is indexed such that the higher bytes of the data will
overlap with the data from another channel. If the WORD or DWORD data is from an
input channel with lower number, the MSB (s) of the data will be overwritten. If it is
from an input channel with a higher number, the MSB(s) of the data will overwrite the
LSB(s) of the other channel.
It is the responsibility of the user to ensure that this doesn’t happen.
WARNING: For Input messages, if the Axiomatic Proprietary B scheme is used, and
the LOWEST index channel has its "Message Type" set to "Command", byte 0 of the
message will always be $0C, and byte 1 will always be set to $01, even when the PGN
is shared. If the Data Index of any of the input channels is set to 0 or 1, the measured
data will be overwritten by the Axiomatic Proprietary B data.
It is the responsibility of the user to ensure that this doesn’t happen.
WARNING: The ECU can only share the same PGN for the same type of messages.
This means that an input measured message MUST NOT share a PGN with an output
feedback message. If this happens, the ECU will not use the multiple channel
message scheme described above, but rather send the PGN twice, once as the input
message, and again as the feedback message.
It is the responsibility of the user to ensure that this doesn’t happen.
