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VT-SBC-3588 | User Manual 23
2.4.16
J34 RS232/RS485 (Phoenix terminal) (16)
The VT-SBC-3588 implements a 6-pin Phoenix terminal (2 x 3 x 3.81mm) configured as two
isolated RS232/RS485 multiplex connectors (UART 4 and UART 7). The two connectors are
identified as /dev/ttyS7 and /dev/ttyS4 in the software system.
Pinout description:
Pin
Name
Type
Description
1
RS485_A_2 / RS232_TX2
RS485_2 A / RS232_2 data output
2
RS485_B_2/ RS232_RX2
RS485_2 B / RS232_2 data input
3
ISO_GND_2
P
RS485_2 / RS232_2 ground_2
4
RS485_A_1/ RS232_TX1
RS485_1 A / RS232_1 data output
5
RS485_B_1/ RS232_RX1
RS485_1 B / RS232_1 data input
6
ISO_GND_1
P
RS485_1/ RS232_1 ground_1
When the connector is in RS485 mode, the jumpers (J33, J35) behind the Phoenix terminal
are used to connect terminal resistors (120
Ω
) in series respectively for UART 4 and UART 7
to prevent signal reflection and improve the signal quality.
Pinout description of J33:
Pin
Name
Type
Description
1
RS485_B_1
RS485_1 B, 120
Ω
resistor connection in
series
2
RS485_A_1
RS485_1 A
3
NC
Pin 1
Pin 4
UART7
(ttyS7)
UART4
(ttyS4)
Pin 1
