User's Manual l MBa57xx UM 0100 l © 2020, TQ-Systems GmbH
Page 25
4.2.6
RS-485
The TQMa57xx UART10 interface is routed to an RS-485 transceiver (SP491E), which provides the signals at the 9-pin D-Sub
connector X7. The RS-485 interface is galvanically isolated with 500 V.
The interface is configured for full duplex operation by default, but can be switched to half duplex by an assembly option.
In this case, the receiver is controlled by UART10_RTS#. The assembly option is shown in the MBa57xx circuit diagram.
Illustration 14:
Block diagram RS-485
Table 26:
Pinout RS-485, X7
Pin
Pin name
Signal
Dir.
Remark
1
A
RS485_A
I
Galvanically isolated
2
B
RS485_B
I
Galvanically isolated
3
Y
RS485_Y
O
Galvanically isolated
4
Z
RS485_Z
O
Galvanically isolated
5
GND
GND_RS485
P
Galvanically isolated
The RS-485 signals can be terminated with 120 Ω using DIP switch S5.
Table 27:
RS-485 termination, DIP switch S5
Switch
ON
OFF
S5-1
Transmit path terminated with 120 Ω
Transmit path not terminated
S5-2
Receive path terminated with 120 Ω
Receive path not terminated