Basler Electric DGC-2020 - Manual (Page 131)

Communications
DGC-2020 communication settings include setup parameters for CANBus, ECU, modem, and RS-485
communication.
CANBus Setup
The DGC-2020 CANBus interface provides high-speed communication between the DGC-2020 and the
engine control unit (ECU) on an electronically controlled engine. When ECU support is enabled
A , the
DGC-2020 will ignore the analog coolant temperature, oil pressure, and engine speed inputs and rely
upon the ECU for these parameters. The DGC-2020 will also stop calculating engine run time and begin
using the run time recorded by the ECU.
When enabled B , the DGC-2020 will receive and retain unsolicited diagnostic trouble codes (DTCs) from
an ECU with DTC capabilities.
Early versions of the J1939 specifications were unclear about how the 19 bits of the SPN were arranged
within their allocated places in the data. While it was clear which bytes and bits contained the 19 bits of
SPN data, it was not clear whether the data within the bytes was arranged with the most significant bit
first or least significant bit first. It was also unclear which byte was most significant and which was least
significant. The ambiguity led to various engine manufacturers adopting three different methods of
converting the data into SPN numbers.
This was remedied in the J1939 specs, and the SPN Conversion Method C bit was added. When this bit is
a zero, the conversion method is indicated as version 4. The DGC-2020 will automatically set the
conversion method to 4 when the CM bit is zero; this occurs for most engine types. However, if the CM bit
is 1, indicating the SPN conversion method is NOT 4, the user will have to consult the engine
manufacturer to learn the correct method of SPN conversion, and set the SPN Conversion Method setting
in the DGC-2020 accordingly.
A DGC-2020 operating on a CANBus network is identified by a unique address number D . The CANBus
Address is set internally by the DGC-2020 when certain types of ECUs are selected on the ECU Setup
screen, and in this case, the user-entered value does not apply. See Table 4-4.
Table 4-4. CANBus Address per ECU Type
ECU Type CANBus Address
Standard User-selectable
Volvo Penta 17
MTU MDEC 6
MTU ADEC 1
MTU ECU7/ECU8 6
GM/Doosan User-selectable
Cummins 220
MTU Smart Connect 234
In applications where the ECU is not continuously powered, the DGC-2020 has provisions for applying
power to the ECU and pulsing the ECU to update its engine monitoring data. Either the DGC-2020 RUN
or PRESTART relay output can be used to apply power to the ECU
E . If the PRESTART contact is
selected, the RUN output will still close during cranking and genset operation to provide a separate
indication that the genset is running. For applications where pulsing of the ECU is not desired, this pulsing
feature
F can be disabled.
The BESTCOMSPlus CAN Bus Setup screen is illustrated in Figure 4-19.
ECU Limitations
For some ECUs, an external source cannot stop the engine without removing power from the ECU.
Turning off power to the ECU is the only way to remove fuel from the engine and shut it down. Different
ECU manufacturers have their own rpm setpoints for reapplying fuel to an engine. If the ECU is powered
up and the engine is still spinning above 60 rpm, then the ECU will automatically turn the fuel on. Detroit
Diesel J1939 ECUs, for example, have a setpoint of 60 rpm.
9400200990 Rev X DGC-2020 BESTCOMSPlus
® Software
4-21