# ECU Monitor
Syrus 4G IoT Telematics Gateway has a built-in ECU interface, which allows the device to connect to a vehicle's CAN bus and read data.
- The way it works is that you instruct the Syrus to read data at a certain speed for a particular protocol, for example read J1939 data at 250KHz from the PRIMARY CAN wires on the device.
- Once the corresponding wires are connected to the vehicle's CAN bus, the ECU will parse the parameters found in the corresponding parameter file inside the device.
- By default Syrus 4G comes loaded with a predefined list of common parameters, but this list is editable by the user, so they can expand or select only the parameters he/she wants.
- Once the parameters are being read you can use an application like SyrusJS to obtain the engine data and send it to an endpoint or create rules/trigger actions based on the values reported.
- You can also use the Syrus 4G to log data from the CAN bus and interpret any proprietary parameters found, provided that you know how to interpret them, more details here.
$ sudo apx-ecu configure [INTERFACE] [PROTOCOL|CAN_MODE]
Example, configure the Primary CAN (CAN1_H / CAN1_L wires) to read J1939 at 500KHz
$ sudo apx-ecu configure PRIMARY_CAN J1939_500KHZ
|PRIMARY_CAN||String||Primary CAN configuration (CAN1_H / CAN1_L wires)|
|SECONDARY_CAN||String||Secondary CAN configuration (CAN2_H / CAN2_L wires)|
|LISTEN_ONLY_MODE||String||Program the listen only mode|
PRIMARY_CAN or SECONDARY_CAN
Listen Only Mode
In this mode the ECU Monitor does not request parameters to the vehicle's onboard computer. This is useful in case there's any interferences caused when connecting a diagnostic tool like the ECU to the vehicle's CAN bus.
Once you've configured the ECU, you're ready to connect it to the vehicle's J1939/CAN bus connector, this is usually a 9-pin connector, refer to our support site for more information on the location of this connector.
CAN Bus Wiring Pinout (found in 14-pin molex)
|Syrus Wire Color||Signal||Description|
|Yellow||CAN1_H||Primary positive signal of the J1939/FMS bus. Connect to the vehicle's CAN_H cable. This cable is twisted together with the green CAN1_L cable.|
|Green||CAN1_L||Primary negative signal of the J1939/FMS bus. Connected to the vehicle's CAN_L cable. This cable is twisted together with the yellow CAN1_H cable on the ECU Monitor.|
|Cyan||CAN2_H||Secondary positive signal of the J1939/FMS bus. Connect to the vehicle's CAN_H cable. This cable is twisted together with the white/light green CAN2_L cable.|
|White||Light green||CAN2_L||Secondary negative signal of the J1939/FMS bus. Connect to the vehicle's CAN_L cable. This cable is twisted together with the cyan CAN2_H cable.|