UM0842
Configuration
Doc ID 16542 Rev 4
13/50
5.4
RS-232 and RS-485 transceivers
There are three RS-232 DB9 plug connectors and one RS-485 DB9 socket connector with a
Profibus DP compliant pinout available on the board.
UART0 features the full modem control signals and fully utilizes U10, U12 and partly U14
RS-232 transceivers. The RS232_0 signals are available through the CN13 connector.
Optionally when the U10 RS-232 transceiver is not soldered on the board, it is possible to
line in RS232_TXD and RS232_RXD signals from the CPU board to the CN13 connector.
UART1 features only RX/TX functionality and is connected to the U14 RS-232 transceiver
which RS232_1 signals are then available from the CN15 connector.
UART2 features only RX/TX functionality and uses U13 RS232 transceiver which RS232_2
signals are available from the CN14 connector. Optionally by setting jumpers JP12 and
JP13, the UART2 RX/TX lines can be connected to the RS-485 transceiver U11 whose
outputs are then available from connectors CN11 and CN12. The RS-485 transceiver U11
can be controlled through GPIO pins PL_GPIO77 (receiver enable, R70 - pull up) and
PL_GPIO78 (driver output enable, R73 pull down). Check the ST3485 datasheet for further
details about all possible transceiver configurations.
Table 5.
CAN1 transceiver settings
Jumper
Description
Configuration
JP4
CAN1 transceiver works in standby mode when JP4 is set.
CAN1 transceiver works in high-speed mode when JP4 is set
(Default).
CAN1 transceiver works in slope control mode when JP4 is
open.
JP5
CAN1 terminal 120
Ω
resistor is enabled when JP5 is loaded.
Default setting: loaded
1 2 3
1 2 3
1 2 3
1 2
Table 6.
UART2 RS-232/RS-485 configuration
Jumper
Description
Configuration
JP11
Co5.0 V to the RS-485 (R71, R72 and R74)
termination network.
Co3.3 V to the RS-485 (R71, R72 and R74)
termination network (Default).
1 2 3
1 2 3
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