SAE J1939 and J1708 is the vehicle bus standard used for communication and diagnostics among vehicle components. Based on the same architecture FMS protocol dedicated to telematics systems is available.
- SAE J1708 is a standard used for serial communications between ECUs on heavy duty.
The hardware utilized is RS-485 transceivers wired for open collector operation through the use of a pullup and pulldown of the separate data lines.
J1708 functionality is used to read vehicle's Fuel Level and Fuel consumption.
Because fuel CAN data J1708 is not a CAN-BUS protocol, FMB640 CAN1 and CAN2 lines cannot be used to read J1708 information. FMB640 has a special J1708 Port, which utilizes an RJ9 4P4C connector.
- FMS CAN data(J1939), or Fleet Management Systems Interface, is a sector to configure and manage events based on vehicle data of commercial vehicles. Vehicle data comes through CAN line.
The FMS standard defines a gateway between the J1939 vehicle network and a fleet management system.
FMS Standard lower layer protocols:
- Application layer – SAE J1939/71
- Data link layer – SAE J1939/21 (FMS data are coded according to SAE J1939)
- Physical layer – ISO 11898-2 High-speed CAN, 250 kbit/s bus speed
- Physical connectors – Not standardized
| time | version | common name | notes |
|---|---|---|---|
| 2002 | 1.0 | Truck FMS Standard | Initial release |
| 2007 | 00.01 | Bus FMS Standard | Specialized for buses and coaches including specific signals like door openings, etc. |
| 2010 | 02.00 | Truck FMS Standard | It took over some signals from the Bus FMS Standard, but still handled separately for Trucks. |
| 2012 | 03 | FMS Standard | Harmonized Bus and Truck standard (with separated sections inside for buses and trucks). |
| 2017 | 04 | FMS Standard | Harmonized Bus and Truck standard (with adding Cruise control states) |
direct J1708/J1939 connection
Teltonika FMB640 FMX640 offers the following options for direct J1708/J1939 connection:
- through the 2x10 socket (front side)
- SAE J1939, CAN 1, FMS
- SAE J1939, CAN 1, raw/manual (i.e. without FMS)
You get raw CAN data from the vehicle CAN lines. Please- configure required data filters on FMB640 and
- setup your server to correctly interpret the raw data received from FMB640.
- SAE J1939, CAN 2, FMS
- SAE J1939, CAN 2, raw/manual (i.e. without FMS)
You get raw CAN data from the vehicle CAN lines. Please- configure required data filters on FMB640 and
- setup your server to correctly interpret the raw data received from FMB640.
- through the J1708 socket (back side, RJ11 port)
- SAE J1708 (actually RS-485 at physical layer)
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references
- FMB640 SMS/GPRS command list
- https://wiki.teltonika-gps.com/view/FMB640_LVCAN_I/O,FMS_IO_and_Tachograph_data_elements
- https://wiki.teltonika-gps.com/view/FMB640_Teltonika_Data_Sending_Parameters_ID#FMS_elements
- https://wiki.teltonika-gps.com/view/FMB640_J1708
- https://wiki.teltonika-gps.com/view/FMB641_CAN_%5C_Tachograph
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FAQ
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Q: Are SAE J1939 ports read only?
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Q: Where do I get the SAE J1939 wiring diagram for a vehicle?
A: Please contact
support@mirifica EU us,
maybe we have the right SAE J1939 wiring diagram for the vehicle.
If not, you shall contact the vehicle manufacturer or one of its authorized service centers.
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A: Check if the power source does provide enough power for device to start, which is 12 Vbetween (10-30) V DC. Then, the device will leave the hibernation state.
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Q: How does the tcp link work in FMB640?
A: TCP link mode works like a "tunnel" connecting RS232 device with the server. FMB640 simply acts like a "data tunnel".
Using TCP link mode, each time RS232 message is received, FMB640 would re-sent RS232 data to the server. This requires that FMB640 is connected to the server 24/7 and always has open data link with the server, because TCP link mode only works when device has open data link with the server.
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Q: Does FMB640 support modbus ?
A: FMB640, FM63 and FMB125 support RS485, can support MODBUS. But functionality is not available, thus special development is required.
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