Mettler Toledo IND780 Installationshandbuch Seite 48

Table 2-3: COM2 Port Connections
Pin Signal
1 TxD RS-232 Transmit data
2 RxD RS-232 Receive data
3 GND RS-232 Signal ground
4 TxD+ RS-422/485 Transmit +
5 TxD- RS-422/485 Transmit -
6 RxD+ RS-422/485 Receive +
7 RxD- RS-422/485 Receive -
8 +12V +12V Out, <0.5 A
Some examples of connecting external equipment are shown in Figure 2-34.
Figure 2-34: COM2 Wiring for External Equipment
RS-485 Transmission Line Termination
The RS-485 network should include a terminating resistor, installed between the
two lines at or on the last node. The terminating resistor should match the
characteristic impedance of the transmission line, approximately 120 ohms. This
terminating resistor is required when connecting ARM100 modules to the port.
IND780 Installation Manual
Function
Jumper to RxD+ for RS-485
Jumper to RxD- for RS-485
Jumper to TxD+ for RS-485
Jumper to TxD- for RS-485
Notes
2-21