Electrical Control System

Electrical Control System General Information

The electronic control system in the machine uses a combination of switches, relays and computer-based components.

The computer-based components communicate with each other using a Controller Area Network (CAN) communication protocol.

CAN System General Information

The electrical system uses the SAE J1939 standard for Controller Area Network (CAN) communication and diagnostics.

CAN is a message-based protocol, allowing communication between devices without the need for a host computer. It provides communication between control system components used throughout the machine.

Devices communicate with each other through a two-wire, serial bus connection (CAN high and CAN low). The wires are 120 ohm nominal twisted pair.

The main components of the CAN system are:

•Display

•MCU (Machine Control Unit)

•ECU (Engine Control Unit)

•TCU (Transmission Control Unit)

CAN allows various devices on the network coordinate functions. For example, CAN messages generated by the ECU are acted upon by the TCU (or vice-versa) to coordinate proper engine/ transmission performance.

Some CAN messages are based on feedback from sensors or controls. Electrical input from a control or sensor is converted to CAN messages which are broadcast on the CAN network and are acted upon by devices on the network. For example, input from the engine coolant temperature sensor is monitored by the ECU. If the sensor input rises above a set level (engine overheat), a CAN message (110-x) is broadcast on the system by the ECU, which is acted upon by devices on the network (error codes/output indicators on the display, possible engine de-rating, etc.).

The CAN system also allows for connecting an external computer for service and diagnostic purposes.