HEM Data Products

J1939 Mini Logger™

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DAWN Mini-Logger Video

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The DAWN J1939 Mini Logger™ is a compact logger that acquires CAN bus data from heavy-duty trucks, buses, and off-road vehicles. It fits directly on the J1939 connector. The J1939 Mini Logger is part of the Mini Logger family of compact, low-cost, data loggers that acquire a variety of data from trucks and cars.

The J1939 standard defines over 5000 parameters that could be on a vehicle’s J1939 network. The companion DawnEdit™ software determines which parameters are available on the vehicle to create a unique database for each vehicle model. The user can select the parameters to acquire. Also, the user can add custom messages and parameters in DawnEdit to acquire proprietary messages. The J1939 logger is capable of logging all messages on the network by default.

Soft LED indicators show the logger status without distracting the driver. It has a real-time clock which the user can set to the local time zone. The Mini Logger includes a battery backup so the logger always knows the correct time.

The DAWN Mini-Logger Video demonstrates how to configure the logger and convert the messages to scaled, engineering parameters.


Standard Parameters

List of J1939 parameters

Some standard parameters need to be requested. The DAWN J1939 Mini Logger supports this function.


J1939 Mini Logger Specifications

SAE J1939 CAN Yes
SAE J1708/1587 Yes
No. of Protocol Ports (Channels) One CAN channel and one for J1708.
Stand-alone Logger Yes
Store Messages Yes. Convert to scaled engineering parameters as a post process
On-board Storage Micro SD card 4GB standard. Up to 32GB allowed.
Auto Start-up Yes
LEDs for status RGB
Operating system Proprietary RTOS
GPS (NMEA 0183) Option. Internal to Mini Logger.
Wireless (Wi-Fi) or equivalent Option. Internal to Mini Logger
Cellular modem Option. Connects with WiFi or serial cable.
Real-time clock (RTC) Yes
Analog Inputs
Internal Temperature Sensor Option
3-axis MEMS Accelerometer Option
Expansion Optional ADAQ Mini
Size (inches)Size (mm) J1939 Connector: 1.5 Diameter x 2.3 Long38.1 Diameter x 58.4 Long
Supply Current: 80 mA. Up to 200mA with WiFi
Operating Temperature C -40 to +70
Operating voltage 6 to 36V
Power Draw while sleeping 3 mA
Warranty 1 Year


Data Storage & Transfer

The J1939 Mini Logger comes standard with a 4GB micro SD card. The card can be as large as 32GB. A USB/micro card reader is provided to manually transfer message files to a PC. The oldest files are removed if the logger runs out of disk space. How to estimate data size


Automated Data Transfers with WiFi and Cellular

WiFi or cellular are options to automate the file transfers to a website. Files are removed after being successfully transferred. If you prefer to use an HEM Data website to store and display data click here for a description of features and benefits.

For details on the WiFi and cellular options click here.



GPS data is an option for the J1939 Mini Logger. GPS Data syncs with vehicle data on conversion. Click here for details on GPS that is housed within the Mini Logger.


Stand-alone Data Logger or Real-Time Display

The DAWN J1939 Mini Logger™ works as a stand-alone data logger for convenient data storage without a PC: just plug the logger into the J1939 connector and it will start storing messages as soon as the ignition is turned on.

If you need real-time display of the data on a PC or smartphone, then you can also use the OBD Mini Logger as a pass-thru device. We also offer a dedicated real-time device, the DAWN Mini Streamer™. The smartphone can then upload the necessary information to a website for summary and analysis over cellular. The Mini Streamer sends OBD, CAN and J1939 data.


Analog Data

The ADAQ Mini acquires analog data directly from sensors and outputs CAN data to an OBD or J1939 Mini Logger. Input types including voltage, current, temperature (thermocouple & thermistor), digital, frequency, PWM, and inclination. Click here for ADAQ details.


Supports J1708

The DAWN J1939 Mini Logger™ supports J1708. Take either simultaneously with J1939 or directly from the 6 pin J1708 connector. HEM Data provides an adapter cable between the 9 pin J1939 logger and the vehicle’s 6 pin J1708 connector.


Future Enhancements

Check with HEM Data for availability for support of these future enhancements: Bluetooth and smartphone. info@hemdata.com



Options include:



J1939 Mini Logger Pins J1939 Truck Adapter
Signal Name Pin
Power B
Ground A
J1708 + F
J1708 – G
CAN Shield E


Logger Comparison

Feature OBD Mini Logger J1939 Mini Logger
16 pin J1962 OBD Connector Yes Needs an adapter cable
9 Pin J1939 Deutsch Connector Needs an adapter cable Yes
CAN channels (networks) 2 Version 3=1; version 4=2
OBD-II J1979 support Yes No
J1939 Support Yes Yes
J1708 Support (older HD protocol) No Yes
Legacy OBD protocols Yes No
Raw CAN (Normal messages, CANopen) Yes Yes
Cellular Yes No
WiFi Yes Yes
GPS Yes Yes
External uSD card for data storage Version 3 Version 3 & 4
Internal data storage only Version 4 No

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