HEM Data Products

Real-time DAWN Mini Streamer™


J1939 Mini Streamer™

The DAWN Mini Streamer™ uses WiFi to transfer data from a car or heavy duty vehicle to a tablet, smart phone or PC to view in real-time. The smart phone can then upload the necessary information to a website for summary and analysis over cellular. The Mini Streamer sends OBD, CAN and J1939 data. The streamer comes in two form factors: with the J1939 or OBD connector.

The Mini Streamer is valuable for the service technician or engineer who wants immediate feedback. It is also valuable to measure vehicle performance on a dynamometer or in service repair shop. The technician can be in or outside of the vehicle.

For more complex logging, the DAWN Mini Logger can upload data in short intervals (i.e. 5 minutes) for near-real time data analysis. The logger sends data to a web-based dashboard that displays the latest data, summarizes the historical data, and automatically provides alerts when user-defined conditions are detected. Example DAWN Dashboards are at http://dashboard.hemdata.com/.

The Mini Streamer can simultaneously acquire and transfer three types of messages:

  • Generic OBD-II – standard on all cars and light trucks after 1996 (mode $01) as defined by J1979
  • Enhanced OBD – similar to a service scan tool database; specific to each OEM (mode $21 and $22)
  • Normal messages – transmitted for normal vehicle operation; no request messages required (These can be any CAN format including J1939 and CANOpen)

The streamer can also transmit GPS data.

J1939 Mini Streamer Specifications

ISO 15765-4 (CAN, 11-/29-bit, 250/500 kbps) Yes
J1939 Yes
J1708 Yes

No. of Protocol Ports (Channels)

One CAN Channel (Autodetect: 250, 500kbps, other)

Real-time PC data


RT Connections to PC


LEDs for status


Operating system

Proprietary RTOS

GPS (NMEA 0183)



Size (inches)

Size (mm)

Weight (g)

J1939 Connector:  1.5 x 1.5 x 1.0

40.1 x 40.1 x 29.1


Supply Current:

80 mA. Up to 200mA with WiFi

Operating Temperature C

-40 to +110

Operating voltage

4 to 30V

Over/Under Voltage protection

-30 to +100V


1 Year


DawnPlot™ and DAWN MessageMonitor™ work with the Mini Streamer.

  • Use DawnPlot to plot engineering values in real-time on a PC or iPhone/iPad. Features include cursors, drag zooming, multiple y-axis overplots, and histograms.
  • Use DAWN MessageMonitor to monitor, summarize, and display network traffic in real-time with a PC or iPhone/iPad. Message Monitor has many analysis features, such as sorting, filtering, and plotting specific bytes within messages.

Also, HEM Data creates custom applications. HEM Data can quote a custom app upon request or we can assist the user in developing one.

DawnEdit™ provides the OBD-II and J1939 databases relating parameters to messages. DAWN MessageMonitor TM will help you develop more advanced databases. Using the two software packages together provides an efficient way to reverse engineer messages and to then summarize your results in a standard DawnEdit database.

Reasons to use Message Monitor:
• Reverse engineering
• Competitive vehicle or subsystem
• Understand broadcasted messages
• Determine message update rate
• Debugging the Controllers on the Network
• Understanding how to initiate Enhanced OBD Diagnostic Session
• Any application where messages are the focus

DawnPlot and MessageMonitor are both available for iPhone/iPad. Also, HEM Data creates custom applications.


Custom DawnPlot iPad App

J1939 Mini Logger™ OBD Mini Logger™ DAWN Telematics™ DAWN™ Software ADAQ Mini™ DAWN Dashboard™