3-24
Installing 505 System Hardware SIMATIC 545/555/575 System Manual
Setting the CPU Dipswitches (continued)
The
545 and 555 CPUs have two communications ports. Both ports are
configured as Data T
erminal Equipment (DTE).
SW2 selects Port 1 as either a programming port or a printer port on a
545/555 CPU. Port 1 uses an RS-232/RS-423 signaling protocol and an
RS-232 pinout arrangement with an RS-423 (+5 V) signal level extending
up to 50 feet (15 m). Y
ou can use a modem to extend this distance.
•
Setting SW2 to the left selects Port 1 as a programming port.
•
Setting SW2 to the right selects Port 1 as a printer port.
Figure 3-13 shows the locations of Port 1 and Port 2 on the front of the CPU.
Port
1
Port 2
Pin Signal
3
9
5
8
2
DO+
DI+
GND
DO–
DI–
Controller
Male 9-Pin D
Type
Port 2
(1)
RS-422 Port Pinouts
Pin Signal
3
8
5
TX/RX+
TX/RX–
GND
Controller
Male 9-Pin D
Type
Pin Signal
1
2
3
4
5
RSD
RCV
XMT
DTR
GND
Controller
Male 9-Pin D
Type
Port 1
RS-232 Port Pinouts
6 DSR
7RTS
8 CTS
Pin Signal
2
3
5
RCV
XMT
GND
Controller
Port 2
(1)
RS-232 Port Pinouts
Male 9-Pin D
Type
Port 2
(2)
RS-485 Port Pinouts
(1)
Dipswitch 1 is On.
(2) Dipswitch 1 is Of
f.
(3) User connection to select RS-232 operation.
120
W
termination resistors
can be used for higher noise
immunity and more reliable
long-distance communication.
6 SEL232*
6 SEL232*
6 SEL232*
(3)
Figure 3-13 545/555
CPU Port Locations
W
ith the 545 and 555 CPUs, your choice of cabling determines whether
Port 2 functions as an RS-232/RS-423 port or as an RS-422/RS-485 port.
Figure 3-13 describes the pinouts required for the various Port 2 options.
If you use RS-422/RS-485 cabling, SW1 on the dipswitch allows you to select
between RS-422 and RS-485. Use SW1 as follows:
•
Set SW1 to the left when you use RS-232 or RS-422 cabling.
•
Set SW1 to to the right when you use RS-485 cabling. RS-485 uses a
single twisted pair to transmit and receive data between the
programming device and the 545/555 CPU. Multiple CPUs or multiple
programming devices (on this RS-485 link) are not supported and must
not be used.
Communications
Port 1
Communications
Port 2
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