User's Manual l MBa7x UM 0101 l © 2020, TQ-Systems GmbH
Page 31
4.2.4
CAN
TQMa7x
Galvanic
isolation
3-pin header
(X10)
CAN 1
CAN 2
CAN
Transceiver
CAN
Transceiver
3-pin header
(X11)
S5-1
120
Ω
S5-2
120
Ω
Figure 20: Block diagram CAN
Both CAN interfaces on the MBa7x are directly connected to the CAN ports of the TQMa7x and made available at the 3-pin
connectors X10 and X11. Both interfaces are galvanically isolated with a dielectric strength of 1 kV.
The CAN interfaces are galvanically not isolated from each other.
The High-Speed mode is configured by default using a configuration resistor at the input RS of the CAN transceiver MCP2551
(390 Ω to Ground
maximum slew rate).
The High-Speed mode supports data rates up to 2 Mbit/s or maximum cable length. When required, the resistor at the RS input
can be increased (10 … 120 kΩ) to reduce the slew rate.
The CAN signals can be terminated with 120 Ω using DIP switches S5-1 and S5-2.
Table 30:
CAN termination, DIP switch S5 settings
Switch
Interface
ON
OFF
S5-1
CAN1
CAN1 terminated with 120 Ω
CAN1 not terminated
S5-2
CAN2
CAN2 terminated with 120 Ω
CAN2 not terminated
Figure 21: Position of CAN – X10, X11, S5
10:
See data sheet MCP2551.
