Emerson CSI 6500 Schnellstartanleitung Seite 11

Product Information / Produktinformation A6824 / A6824R
Gateway Card
RS 485
For faultless operation of an RS 485 bus, electrical terminations at the first and last device of
the bus are required. This means that a 120 Ohm resistor must be installed between lines "A"
and "B" next to the A6824 / A6824R interface converter and at the physically last device on the
bus. Additionally, at the first or last device of the bus, the line "A" must be connected to +5V via
a pull−up resistor and the line "B" to ground via a pull−down resistor.
With use of the A6824 this can be done with plug−in jumpers, on the gateway−card. The figure
shows the position of the jumpers for the 6 RS 485 bus lines.
To activate the bus terminator and to place the lines "A" and "B" on the references, plug the
jumpers as shown in Fig. a). Fig. b) shows the jumper position for deactivated bus termination
and open references.
• Jumper 1−2 closed: Line "B" of the bus is connected to ground via a pull−down resistor
• Jumper 3−4 closed: 120 Ohm resistance between "A" and "B"
• Jumper 5−6 closed: Line "A" of the bus connected to +5 V via pull−up resistor
J1
TRACO
1
3
5
TRACO
a)
2
4
6
Bus line 1
Bus line 2
Bus line 3
Bus line 4
Bus line 5
Bus line 6
J1
TRACO
1 2
3 4
5 6
TRACO
b)
Page 11