August 28, 2020  J1708 Gateway Update

The latest version brings Cummins KCM II support, exhaust gas and ambient temperatures for KCM and J1587 engines, and negative engine hours offset in options.

KCM-II Engine Meter

The KCM II (including models KCM-IIR, KCM-IIG) is the control unit used with Cummins marine engines and gensets, like KTA19 and KTA38. The J1708 Engine Gateway can be connected to the RS485 output of the unit to get the following set of data:

  • engine revolutions;
  • running time;
  • coolant temperature;
  • oil pressure and temperature;
  • battery voltage;
  • exhaust temperature;
  • ambient temperature;
  • alerts and warnings.

The KCM II protocol is detected by Gateway in AUTO mode, but you can turn it on manually in the configuration file:


Exhaust gas temperature and ambient temperature are also transmitted by some J1578 engines (but not by Volvo Penta KAD/TAMD engines) and can be sent by the Gateway to NMEA 2000 in PGN 130316. We added two new parameters to the configuration file:


The data instance in transmitted messages matches the engine instance setting, and our Web Gauges, for example, can display exhaust gas temperature from twin engines. For the ambient temperature (factory setting is OFF) you should specify the temperature data type from 0 to 252 to turn in on:

  • 00 = Sea Temperature
  • 01 = Outside Temperature
  • 02 = Inside Temperature
  • 03 = Engine Room Temperature
  • 04 = Main Cabin Temperature
  • 05 = Live Well Temperature
  • 06 = Bait Well Temperature
  • 07 = Refrigeration Temperature
  • 08 = Heating System Temperature
  • 09 = Dew Point Temperature
  • 10 = Wind Chill Temperature, Apparent
  • 11 = Wind Chill Temperature, Theoretical
  • 12 = Heat Index Temperature
  • 13 = Freezer Temperature
  • 14 = Exhaust Gas Temperature
  • 15 through 128 Reserved
  • 129 through 252 Generic Temperature Sources other than those defined

For example, to transmit ambient temperature as "Engine Room Temperature", use the following setting:


The KCM II unit has three user-defined standby switch alarm output channels (in addition to oil pressure and temperature, coolant temperature, battery voltage and other alarms) which are mapped to the following NMEA 2000 engine statuses: "Warning Level 1", "Warning Level 2" and "Maintenance Needed". All NMEA 2000 warnings and alarms can be masked with the Gateway's ENGINE_ALERT_MASK setting.

KCM-II Engine Meter

Figure 1. Gateway's data on Maretron dashboard

During the last two weeks, the firmware has been tested on mega yacht with two Cummins engines and equipped with Maretron software (see the image above).

And the last addition in the new update is the possibility to specify negative engine hours offset. For example, to reduce engine hours displayed by one hour (3600 seconds), add the following setting to the configuration file:


This setting is useful when you have replaced the engine control unit with a used one and need to get your own readings to match with the actual engine hours.

Firmware update for J1708 Engine Gateway (1.05), is available at Downloads section.


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