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COM128 Installation and Operation Manual Schneider Electric
7
4.2.2 DIRECT CONNECTION
TO A COMPUTER
PORT SELECTION
An IBM-compatible PC acts as a DTE (Data Terminal
Equipment) RS-232 device. Therefore, the computer’s RS-232
port should be connected to the DCE port on the COM128.
Refer to Figure 4.2.2.
SWITCH SETTINGS
To properly communicate with the computer, the COM128
must be configured as a DCE (Data Communications
Equipment) RS-232 device (see subsection 3.2.1, 'RS-485 Flow
Control').
4 INSTALLATION
4.1 DC SUPPLY CONNECTIONS
The COM128 is shipped with a 9 VDC adapter which plugs
into the adapter receptacle. Use only the adapter provided
with the COM128 for this particular powering application.
Alternatively, any DC power supply capable of supplying
from 9 to 30 VDC at 500 mA (minimum) can be used to
power the COM128. Connect the (+) and (-) outputs from
the power supply to the corresponding terminals of the
removable 2-pin terminal block connector supplied with the
COM128 (See Chapter 2, Figure 2.1.1).
4.2 RS-232 CONNECTIONS
& CONFIGURATION
Sections 4.2.2 and 4.2.3 discuss RS-232 port connections
when connecting to a computer or modem. The COM128
configuration switches are used to select which port is active.
Note that the COM128 can also be used in other applications
by selecting the appropriate port and modes as described in
Chapter 3. For configuration switch settings, refer to section
3.2, 'Mode Descriptions'.
4.2.1 RS-232 CABLE
A standard RS-232 serial communications cable should be
used. The COM128 end must be a female DB9 connector for
direct connection, or a male DB25 for connection via the
supplied adapter plug. Maximum cable length is 50 feet
(15.2 m).
SHLD
PORT C
PORT D
PORT B
PORT A
DCE
PORT
DTE
PORT
RS-232
RS-485
COM128
RS-232 to RS-485 Converter
To
RS-485
Bus
RS-485 Cable
AWG 22 shielded twisted pair.
Total length: 4000 ft. maximum.
RS-232 Cable
50 ft. max.
IBM PC
Figure 4.2.2 RS-232 Direct Connection to Computer