Uf251_01d_oi_e.doc / Aug-16
Page 9 / 25
3.4.
Serial Interface
The unit provides a RS232 interface and a RS485 interface. However, only one of both can be
used at a time. Serial communication allows to read out the conversion result and to set
parameters and variables by PC, according to need.
The serial interface configuration is selected by DIL switch position 1. Position 6 of the switch
selects the communication functions “PC-mode” or “printer-mode”
5
4
3
2
1
9
8
7
6
GND int.
TxD
RxD
RS232
+5V
T+
T-
R+
R-
RS485
Sub-D-9 (female on unit site)
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
GND
TxD
RxD
PC
UF 251
RS232:
Please connect only pins 2, 3 and 5 !
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
T+
T-
120 Ohms
120 Ohms
RS485- Bus
( 4- wire )
UF 251
120 Ohms
120 Ohms
R+
R-
T+
T-
R+
R-
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
T+
T-
120 Ohms
120 Ohms
RS485- Bus
( 2- wire )
UF 251
