Dataforth SCM9B-A2000 Series Manual del usuario - Página 4
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S C M 9 B - A 1 0 0 0 / 2 0 0 0 R S - 2 3 2 D B - 9 C O N N E C T O R
The SCM9B-A1000 and SCM9B-A2000 contain a female DB-9
connector normally used with modems or other Data Communications
Equipment (DCE). This connector should be connected to a host
computer, or controller, when converting RS-232 signals to RS-485. The
Transmit, Receive and Ground signal lines are all that is required for
proper RS-232-to-RS-485 operation. The remaining RS-232 flow control
signals Carrier Detect (CD), Data Set Ready (DSR) and Clear to Send
(CTS) are internally biased to their ACTIVE, or high, using 330 Ohm
resistors connected to +10Vdc. The RS-232 connector pinout is listed
below.
Pin #
Description
1
(CD)
2
(TX)
3
(RX)
4
(NC)
5
(GND)
6
(DSR)
7
(NC)
8
(CTS)
9
(NC)
The RS-232 connector is left open when the SCM9B-A1000 or SCM9B-
A2000 is used as an RS-485 Repeater.
The only connections normally required for proper SCM9B-A1000
operation are pins 2, 3 and 5 of the DB-9 connector. DB-9 to DB-25
adapters can be made using the connections below.
DB-9 Pin #
2
3
5
S C M 9 B - A 1 0 0 0 / 2 0 0 0 R S - 4 8 5 I N C O N N E C T O R
The SCM9B-A1000 and SCM9B-A2000 converters contain a four-pin
screw-terminal plug labelled RS-485 IN. This connector is considered the
HOST input when using the SCM9B-A1000 or SCM9B-A2000 as a RS-
485 repeater. An RS-485 repeater is necessary to extend the length of
an RS-485 network, or connect more than 32 RS-485 devices on an RS-
485 network.
The RS-485 IN data lines should be attached to the end of an existing
RS-485 network. The serial data received on the RS-485 IN data lines will
SCM9B-A1000 & SCM9B-A2000 USERS MANUAL 4
CARRIER DETECT
TRANSMIT DATA
RECEIVE DATA
NO CONNECTION
SIGNAL GROUND
DATA SET READY
NO CONNECTION
CLEAR TO SEND
NO CONNECTION
DB-25 Pin #
3
2
7