CRE Technology GENSYS 2.0 - Communication; Can Bus Good Practices; Figure 75 - Network Topologies; Table 52 - DB9 Pin out

A53 Z0 9 0020 L En Technical documentation
Chapter : Communication
155
15 Communication
15.1 CAN bus good practices
This chapter describes rules to be used to ensure reliable CAN communication. These rules must be applied
to all CAN communications; including inter-GENSYS 2.0 CAN bus (COM1) and ECU/remote I/O CAN bus
(COM2).
Table below lists the standard CAN DB9 wiring compared to GENSYS 2.0 DB9:
Terminal
GENSYS 2.0
Standard CAN
Mandatory
1
NC
Reserved
2
CAN-L
CAN-L
X
3
GROUND-1
CAN GND
X
4
NC
Reserved
5
GROUND-2
CAN SHLD (optional)
6
GROUND-1
GND (optional)
7
CAN-H
CAN-H
X
8
NC
Reserved
9
NC
CAN V+ (optional)
SHIELD
GROUND
X
Table 52 - DB9 pin out
15.1.1 CAN bus cable
Cables used must be selected to respond to CAN bus specificities. Always use 120Ω shielded twisted wire
pairs. Shield should be connected to the metallic connectors of the cable. CAN bus must be deployed in a
single line way (no star, ring or mesh connection) as shown below:
Network topologies
Bus
Mesh
Ring
Star
Figure 75 - Network topologies
Both ends of the CAN bus must be terminated with 120Ω resistors. Such resistors are fitted into GENSYS 2.0
COM1 and COM2 and can be activated using DIP switches at the rear of the module under the “OFF /
120Ω” plug. Termination resistor is connected to the CAN bus when the switch is set to ON (“120Ω” side).
When the switch is set to OFF, resistor is disconnected from the CAN bus.
Figure below gives the example of 3 CRE Technology modules connected through CAN bus. Terminal
resistors must be activated as shown on the 2 modules located at both ends of the CAN bus.