SIREC D Display Recorder 7ND4000

Installation and Wiring
2.3.5 Serial Port - RS232 or
RS485 (Option) - The recorder may be
fitted with a serial communication option, either
RS232 or RS485. The RS232 connection requires
a standard DB9 Female connector and connects to
an IBM PC compatible computer using a null
modem cable and can support cable runs up to 50
feet (16m). The RS485 connection is via two wire
(twisted pair) cable and can support cable runs up
to 4000 feet (1300m). The RS232 Connections to
the DB9 female connector are as follows:
Table 2-2 RS232 Connections
2-8
DB9
Pin
Connection
Direction
To
Modem
pin
(DB25)
To
Computer
(DB9)
2 Rx Data In 3 3
3 Tx Data Out 2 2
5 Common Common 7 5
7 RTS Out NC 8
8 CTS In 4,5 7
103697MA
RS232
2 - RxD
3 - TxD
5 - Com
7 - RTS
8 - CTS
Figure 2-11 RS232 Interface Option
A. Connecting RS232 to Remote
Computer - When connecting to a remote
computer, connect that computers RTS and CTS
lines together and connect only pins 2,3 and 5 from
the recorder. The recorder TxD line goes to the
computer RxD line, and the recorder RxD line goes
to the computer TxD line. The common is
connected at both ends. A null modem cable with
female connectors both ends can be used to
connect the recorder to an IBM compatible
Personal Computer. Connections to a modem are
shown in Table 2-2. Figure 2-11 shows the RS232
Interface option.
B. Connecting RS485 Terminal - The
RS485 line connection has a positive (B) terminal
and a negative (A) terminal, with the red cable
going to the (A) terminal. This option has an
internal terminating resistor which may be
connected to the line by switching either of the two
switches, above the connector, to ON. Refer to
Figure 2-12 for an example of the RS485 option.
1
2
ON OFF
RS485
120 Ohm
Termination
NOTE
B (+)
A (-)
1 0 36 9 8 M A
Figure 2-12 RS485 Interface Option
Both switches must be OFF to disconnect
the resistor (default position).
Up to 31 recorders and or other RS485 compatible
devices may be connected to the line. Only the first
(usually the controller) and last units on the line
must have the terminating resistors switched in,
and then only for long cable lengths. The type of
cable used will limit the data rate and distance. For
this unit, 24 AWG polyethylene twisted telephone
cable that has a shunt capacitance of 16pF/ft
(52pF/m) will allow the full distance of 4000 feet
(1300m).
Siemens AG C79000-G7374-C211-01
SIREC D Manual