Touch-it CE
Operating Instructions
Christ Elektronik GmbH
29
/
37
www.christ-elektronik.de
Tel.: +49 8331 8371-0
4.7
COM2 (RS-232 or RS-485)
INFORMATION!
The interface COM2 can be used as EIA-485 as well as EIA-232 over
software settings.
The following GPIOs must be set with Tegra 2 CPU:
Function
GPIO_C6
GPIO_C1
RS-232 Signals
Low
Low
RS-485 Signals
High
Low
Type
RJ45 Tab-up
Pin
Function
Description
1
GND
Ground
2
GND
Ground
3
A(+)
RS-485 Data+
4
TxD
RS-232 Transmit Data
5
RxD
RS-232 Receive Data
6
B(-)
RS-485 Data-
7
n.c
8
n.c.
INFORMATION!
For writing via RS-485 the GPIO_K7(Tegra T20) must be set “High” and for
reading the GPIO must be set “Low”.
The switch above the COM2 Connector enables the termination
resistor (120Ω) between the A(+) and B(-) signals of the RS-485.
Position SW2
Description
OFF
„left“
RS-485 Termination Off
ON
„right“
RS-485 Termination On
