Apogee Subsea
– Hardware Manual
APOGEESUBSEAHM.1.1
4.3.2. RS-422 basic communication
Below is shown the main interface (Port A) connection, using a full duplex RS-422 connection using the
standard cable provided with the Apogee Subsea. See section Appendix A: Ordering codes and Accessories
for more details about this cable.
Note the termination resistors (Usually 120 ohms) that can optionally be placed on receiver side to avoid
communication errors in long distance communications. These resistors can be omitted in short distance
communications in order to reduce power consumption.
4.3.3. GNSS connection in RS-232 mode
For this typical connection, a shielded AWG 26 cable should be used. Depending on PPS signal strength, we
do not recommend this cable to measure more than a few meters. For long distance, PPS signal and GPS
NMEA signals should be separated in two cables for better noise immunity.
4.3.4. Triggering external devices with the sync Out
Consider a camera that must take a picture when an event is provided on Event Out pin. Event Out and Sync
Out are “open drain” outputs, which means a pull up resistor must be used on receiver side, as shown on the
diagram.
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Figure 4.3: Main serial interface full duplex connection in RS-422 mode
R2
R1
INS
PC
GND
PORT A Tx+
PORT A Tx-
PORT A Rx+
PORT A Rx-
PC Rx-
PC Rx+
GND
PC Tx-
PC Tx+
R1 and R2 are optional. Recommended
for long distance communication
Figure 4.4: Typical wiring diagram for Apogee M / U with external GNSS receiver
INS
GND
PORT B Sync
PORT B Rx
GPS
GPS Tx
PPS
GND
Figure 4.5: Sync Out connection with pull up resistor
INS
GND
Event Out
Camera
Event In
GND
R
VCC < 20V
Pull up resistor must be connected
to Event Out to define High level
