Accessory J1939 Data Link

Accessory J1939 Data Link

The Accessory J1939 Data Link is supported by the EMCP 3.2 and EMCP 3.3.

The Accessory Data Link is used for local or remote communication among modules associated with a single genset. These include a Resistance Temperature Device (RTD) Module, a Thermocouple Module, up to four Digital Input/Output Modules, and up to three Annunciators. The Accessory J1939 Data Link utilizes the Society of Automotive Engineers (SAE) J1939 protocol and requires hardware compliant to the high-speed Controller Area Network (CAN) 2.0B protocol defined in the International Standards Organization (ISO) 11898-2 document, running at 250k bits per second.

The Accessory J1939 Data Link supports appropriate SAE J1939 Broadcast Parameter Group Numbers (PGN) and Suspect Parameter Numbers (SPN) for engine and genset data and diagnostics.

Wiring

The Accessory J1939 communication wires are brought out of the EMCP 3 as part of the 70-pin AMP connector. The pins, as designated on the AMP connector, are shown in Table 1.

Table 1: Accessory J1939 Data Link on 70-pin connector

Pin # Name Description

62 CAN2 + Differential (+) for CAN 63 CAN2 SH Shield for CAN 64 CAN2 - Differential (-) for CAN

Network Topology

The physical topology of the CAN network used in the Accessory J1939 Data Link is a bus topology, consisting of a main trunk and small drops. The maximum allowable trunk length is 800 ft (approx. 250 m), and the maximum drop length is 3 ft (approx. 1 m). The CAN network requires a termination resistor on the extreme ends of the main trunk. The topology for the EMCP 3.2 and EMCP 3.3 in the default configuration, with no remote devices connected, is illustrated in Figure 24 above. The topology for the EMCP 3.2 and EMCP 3.3 with some remote devices connected is illustrated in Figure 25. Note that more remote devices can be connected, as long as the proper lengths are maintained, and the termination resistor is placed at the end of the trunk.