Marathon Electric DVR 2000E+ - Section 8 - Can Bus Interface; Message Format

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Marathon Electric (a division of RBC Manufacturing Corp.) reserves the right to change specications and this manual without notice.
Revised 06/2011
SECTION 8 – CAN BUS INTERFACE
The DVR
®
2000E+ utilizes a CAN BUS interface for reporting metered quantities and providing set point control.
TheprotocolfortheCANisCAN2.0BwiththeJ1939SupersetperISO11898,SAEJ1939-11andSAEJ1939-21.
MESSAGE FORMAT
The message format for the DVR
®
2000E+ is the 29-bit extended frame identifier followed by 8 bytes of data.
All messages use the Proprietary PDU2 Format in Section 5.3 of SAE J1939-21, Revision APR 2001. For the
DVR
®
2000E+ protocol, the 29 bit identifier is defined as follows:
 • ThePriorityBitseldisuser-settablefrom0-5foragivenmessagegroup.
 • TheReservedBit(R)issettozero(0)forallmessages.
 • TheDataPage(DP)bitissettozero(0)forallmessages.
 • TheProprietaryPDU2Formatbyteis0xFFforallmessages
 • ThePDUSpecicbyteisuniquelydenedforeachmessageasagroupextenderofthePDU2format
 • TheSourceAddressistheuser-settableregulatoraddressforoutboundmessagesortheaddressofthe
control ECU communicating to the regulator for inbound messages
The message identifier field is followed by 8 bytes (64 bits) of data. No message shall require more than one pack-
et to complete the exchange of data. Multi-packet messaging is not used in the DVR
®
2000E+ protocol. Message
contentsinthetablesbelowdenedas“0x??”indicateavariablequantitywithinadatabyte.Fixedquantitiesare
identiedwhereapplicable.Bydefault,unuseddatabytesarelledwiththe“0xFF”byte.
The source address for the DVR
®
2000E+ and the electronic control units (ECUs) that it responds to can be edited
in the Windows® communication software. The default DVR
®
2000E+ address is 0 and the range is 0-255d. The
regulator will respond to messages from up to three different ECUs with addresses also in the range 0-255d.
Outbound messages from the DVR
®
2000E+ are divided into 4 message groups: meter, control, generator
status and regulator status. Inbound messages are not included in these groups. Each of these groups has a
configurable message rate and data priority. Priority has a default value of 0 but can be in the range of 0-5.
Message transmission rates are editable as follows:
 • MeteringGroup(0.05–2.0sec,default0.3)
 • ControlGroup(0.025–1.0sec,default0.3)
 • GeneratorStatusGroup(0.5–15.0sec,default5.0)
 • RegulatorStatusGroup(0.1–5.0sec,default1.0)