Other Devices To Serial Interface; Direct Rs232 Interface Connection (I.e. Pc Com Port) - Elster EK280 Applications Manual

EK280

7.4 Other devices to serial interface

7.4.1 Direct RS232 interface connection (i.e. PC COM port)

i
Please follow the application instructions in Chapter 7.4.1.2 "EK280 jumpers" to the letter, to
prevent measurement interference.
7.4.1.1 Connection
EK280
* In place of DTR you may use RTS (DB-9: Pin 7, DE-25: Pin 4). The signal must run continuously at
positive voltage (high-signal) throughout the data transfer. RI may not be used!
In EK280 battery operation the signal is switched off again (voltage ≤ 0 V, low signal), in order to preserve
the EK280 battery's life.
7.4.1.2 EK280 jumpers
X6: No jumper
or one jumper on the pins located
near the terminals
Connectible RS232 interface devices often have a direct or capacitive ground potential connection. There is
therefore a risk of interference coupling via ground loops, which may affect pressure and temperature
measurements.
The position of the two jumpers on X5 by the terminals means that the EK280 interface is electrically isolated
from the rest of the circuit and therefore electromagnetic interference coupling is prevented.
The current required by the EK280 interface of around 1 to 2 mA is therefore supplied by the signal connected
to the "Ri" terminal.
Application Manual
TxD
DTR
RxD
DCD
Ri
GND
Uext+
Uext-
X5: No jumpers
or two jumpers on the pins located closer to the
terminals
("Park Position")
DB-9 DE-25
3 2 TxD
2 3 RxD
4 20 DTR*
5 7 GND
106
PC, laptop or other
RS232