User manual

NMEA Data Multiplexer - NDC-4-A & NDC-4-A -USB
Page 11© 2009 Active Research Limited
Other Connections
Figure 3 – RS232, USB and Battery connections
Connecting to a Personal Computer
The USB port can be used to connect a PC to the NMEA
0183 system.
The NDC-4 should be used with the 2 metre USB cable
supplied as standard. If a longer cable length is required,
a standard USB 1.1/2.0 extension cable should be used
in conjunction with the existing USB cable. This extension
cable would have female ‘A’ and male ‘A’ connectors.
Alternatively, Port 0 (OPTO IN 0 and ISO OUT 0) can
be used to connect a PC into the NMEA 0183 system
by using a serial port cable conforming to the following
specication:
1. A D-type female (socket) connector for the PC end of
the cable.
2. A minimum of 3 cores are required in a shielded cable.
Higher quality cable will yield higher performance
(SNR). Most typical cables have two twisted pairs
inside. In this case, use one pair for the TX line and
one for the RX line. Use the spare wire in each pair
as ground, and connect the cable shield to ground
only at the computer end. Please note that both the
Rx and Tx grounds on the NDC-4 must be connected
to the PC’s ground, as shown in gure 3 above.
3. The TX of the NDC-4 should be connected to the
RX of the computer (standard D-type, pin 2) and
the NDC-4 RX should be connected to the TX of the
computer (pin 3). The GND of the NDC-4 should be
connected to the PC’s serial port ground (pin 5).
Connecting to the battery supply
The Actisense NDC-4 can be powered either by the USB
connection or through an external power source. If both
power sources are available, the current drawn from the
USB supply will be reduced to a trickle. If the external
power source is removed, the USB power will seamlessly
take over, without loss of data.
If the NDC-4 is powered from an external power source, like
a battery, it should be wired to the vessel’s battery supply in
the most direct manner possible, to minimize interference
from other electronic devices. The cable used should be of
sufcient gauge to handle the power requirements of the
Actisense NDC-4 (refer to the Specications sections).
Note:
1. Wire colours are for guidance only.
Battery /
Power Supply
+
-
PC or
Laptop
USB
PC or
Laptop
RxTx G
CAUTION!
The USB power and battery power are NOT
isolated from each other. The USB and external
battery should NOT be connected at the same time
unless an isolated power supply is used.
For installs where the NDC-4 must still operate
when the PC is switched off, full PC isolation can
be maintained by using Port 0 (‘OPTO IN 0’ and ‘ISO
OUT 0’) as the PC connection.
!