UMAX090690. Version: 1.2 Preliminary Documentation
– May Be Subject To Change
18-37
4.5.
CAN Transmit Function Block
The CAN Transmit function block is used to send data from the battery charger to the J1939 network.
Normally, to disable a transmit message, the
Transmit Repetition Rate
is set to zero. However,
should the message share its Parameter Group Number (PGN) with another message, this is not
necessarily true. In the case where multiple messages share the same
Transmit PGN
, the repetition
rate selected in the message with the LOWEST number will be used for ALL the messages that use
that PGN.
By default, all messages are sent on Proprietary B PGNs as broadcast messages. If all the data is
not necessary, disable the entire message by setting the lowest channel using that PGN to zero. If
some of the data is not necessary, simply change the PGN of the superfluous channel(s) to an
unused value in the Proprietary B range.
Since the defaults are PropB messages, the
Transmit Message Priority
is always initialized to 6
(low priority) and the
Destination Address (for PDU1)
setpoint is not used. This setpoint is only
valid when a PDU1 PGN has been select, and it can be set either to the Global Address (0xFF) for
broadcasts or sent to a specific address as setup by the user.
Enabling the
Override Source Address
, allows the
Source Address
of the J1939 Identifier to be
changed to any value between 0…255.
The
Transmit Data Size
,
Transmit Data Index in Array (LSB)
,
Transmit Bit Index in Byte
(LSB)
,
Transmit Resolution
and
Transmit Offset
can all be used to map the data to any SPN
supported message by the J1939 standard from any
Data Source
of the Transmit function block.
Table 5 exhibits the possible
Data Sources
for use in CAN Transmits.
Value Control Source
0
No Control Source
1
CAN Receive
2
Constant Discrete Signal
3
Constant Continuous Signal
4
Power Supply Voltage
5
Charger Feedback Voltage
6
Charger Feedback Current
7
Charger Configuration
8
Charger Mode (See Table 2)
9
Charger Temperature
10
Charger Error Signal
Table 3
– CAN Transmit Data Sources
The battery charger supports up to 5 unique CAN Transmit Messages, all of which can be
programmed to send any available data to the CAN network. Each CAN Transmit Message is setup
to send data from 4 configurable sources, and if each of the 4 sources is used, each source can
have a size as large as 2-Bytes. Only the first 2 CAN Transmit Messages are configured by default,
with the remaining 3 set to unused; the default list is shown in
