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V2
AC500 Hardware
1-35 System
data
AC500 / Issued: 05.2007
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2
3
4
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2
3
4
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2
3
4
1
2
3
4
Slave at the
bus line end,
Master within
the bus line,
Slave within
the bus line
Slave at the
bus line end,
bus termination
120 Ohms
pull-up and
pull-down
bus termination
120 Ohms
activated
120
Ohms
120
Ohms
Figure: RS-485 bus with the master within the bus line
The following photo shows a wiring example "master within the bus line".
Figure: "Master within the bus line", wired at the COM1 bus connector of the Terminal Base
Attention:
If the bus is operated with several masters, the pull-up and pull-down resistors may
only be activated at one master.
The earthing of the cable shields of the bus lines are described in the chapter "CS31 system bus" of the
AC500 system data.
CS31 system bus
Connection of the AC500 CPU to the CS31 system bus using COM1 of the Terminal Base
The AC500 CPU can be used as a CS31 bus master. The connection is performed via the serial
interface COM1 used as a CS31 system bus. The following drawing shows the connection of the bus
signals BUS1 and BUS2.
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5
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8
9
Term. P
Term. N
RTS
TxD
SGND
RxD
CTS
Receive/Transmit, positive
Receive/Transmit, negative
Terminator N
RS-485
RS-485
RS-485
RS-485
RxD/TxD-P
RxD/TxD-N
BUS1
BUS2
L+
M
L+
M
FE
+24 V DC
0 V
+24 V DC
0 V
Functional Earth
UP
UP
ZP
ZP
FE
FE
0 V
24 V
ZP/UP
COM1
Supply voltage 24 V DC, 5-pole, terminals
COM1 9-pole, terminals
as
CS31 bus
Terminator P
Figure: AC500 CPU connected to the CS31 system bus via the serial interface COM1