Pre-deployment Tests

Prior to buoy setup and deployment, it is essential to test the monitoring system (sensors, data logger and telemetry) on shore. This is the most important part of the setup process because it allows users to familiarize themselves with the system while confirming that everything is operating properly. Connect all sensors, power the system, and gather sets of sample data with iChart software. Refer to the SDL500 and iChart categories for additional information on setup and testing of the software, data loggers and sensors. Systems may also ship with project-specific startup documentation provided by NexSens Customer Support.

Before deploying a CB-400 data buoy , it is very important for the user to become familiar with the hardware connections and operation of the system with iChart software. To begin, lay out the buoy, sensors, data logger, and other components that make up the CB-400 system. Follow the steps below to test and assemble the system.

System Connections – Power, Communications and Sensors

CB-400 data buoys are designed to accommodate the SDL500 Submersible Data Logger for connection of monitoring instruments. On CB-400 systems without solar charging, the SDL500 is powered with D-cell alkaline batteries. A communications antenna may be installed in the SDL500 top bulkhead port for radio, cellular or satellite telemetry systems. Sensor connections are made on the top port and/or the five ports on the bottom bulkhead. All sensors and devices must have a NexSens UW connector factory installed in order to connect to the SDL500.

Consult the SDL500 manual for detailed information on the port characteristics to aid in assigning sensors to the appropriate ports. The available ports are shown in Figure 1 below.

SDL Port Connections

Figure 1: SDL500 Bottom (left) and Top (right) Bulkhead Ports

CB-400S systems include an RBP500 Rechargeable Battery Pack and a solar charging kit comprised of three 10-watt solar panels and a power harness with solar regulator. Figure 3-2 is a schematic drawing showing how these components are connected together along with the SDL500.

The three 10-Watt solar panels are harnessed together and connected to a solar regulator. This assembly is connected to Port D on the RBP500. Pass-through signals are enabled on the bottom bulkhead of the RBP500 by connecting UW-1P cables from the SDL500 to the RBP500 top bulkhead as shown. The CB-400S package includes (1) UW-1P cable that connects from Port P0 on the SDL500 to Port P0 on the RBP500 top bulkhead. This enables sensors to be connected to Port P0 and Port D on the RBP500 bottom bulkhead.


Figure 2: CB-400S Power & Communications Schematic

Additional ports can be enabled on the RBP500 by connecting additional UW-1P cables. For example, to enable Port P1 on the RBP500, a UW-1P cable must connect the SDL500 Port P1 to the RBP500 top bulkhead Port P1. To enable Port T on the RBP500, a UW-1P cable must connect the SDL500 Port T to the RBP500 top bulkhead Port T.

Port A, the Analog sensor port, is not available on the RBP500 because it is used as a vent for the battery. Sensors with analog outputs can only be connected to Port A on the SDL500.


Basic Setup

The basic setup for a CB-400 buoy system requires installing sensor cables, connecting sensors and the RBP500 to the SDL500 data logger, installing the SDL500 in the buoy tower, securing the buoy lid, and installing protective pipe caps. The following steps walk the user through this process.

Warning: The buoy is very heavy. Take care to lift properly and wear necessary lifting gear (e.g., back braces). Always wear gloves when handling the buoy to protect hands as the buoy may have sharp edges or points. Three people are required for safe lifting.


Running Sensor Cables

The buoy has three 4” PVC sensor deployment pipes for deployment of water monitoring instruments. Starting at the bottom of a sensor deployment, feed sensor cables up and into the center chamber of the buoy tower. The cables enter the center chamber through a small slot. Be careful to keep the slot in the sensor deployment pipe lined up with the slot of the buoy tower throughout buoy setup.


  Feeding Sensor Cable into Buoy Tower        Feeding Sensor Cable into Buoy Tower

Figure 3: Feeding Sensor Cable into Buoy Tower

After feeding sensor cables into the center chamber, reach down into the buoy tower. Grab the cables and pull them through the buoy tower opening (top). On a CB-400S package, the chamber will also have a UW-1P cable coming from the top of the RBP500.


 Sensor Cable and UW-1P Cable

Figure 4: Sensor Cable and UW-1P Cable


Installing the SDL500 Submersible Data Logger

For SDL500 versions with wireless telemetry (radio, cellular or satellite), an antenna must be connected to the top port.  No antenna is needed for the direct-connect SDL500. Instead, the port is plugged or used to connect a topside sensor.

Important: Double check that there is an O-ring installed on both the antenna plug and at the bottom of the port. The double O-ring seal ensures that connections do not leak. Install the antenna carefully to avoid damaging the pins. Consult the SDL500 manual for additional information on antenna installation.


SDL Top Port Pins   Connecting SDL500 Antenna

Figure 5: Top Port Pins and O-ring and Connecting SDL500 Antenna

Unscrew the plugs from ports that will be used on the bottom of the SDL500. Store them with the SDL500 maintenance kit for future use. For CB-400S systems, Port P0 will always be used to connect to the RBP500 with the UW-1P cable. Remove the large orange O-ring at the bottom of the SDL500. Keep with the SDL500 maintenance kit.


SDL500 with Port Plugs removed        SDL500 with Bottom O-ring removed

Figure 6: SDL500 with Port Plugs and Bottom O-ring Removed

Connect the UW-1P cable running from Port P0 on the RBP500 to Port P0 on the SDL500. Connect additional sensor cables to the appropriate ports. Refer to the SDL500 manual for additional information on sensor-specific port selections. Again, double check for the O-rings on all UW plugs and ports.

Carefully slide the SDL500 into the center chamber of the buoy tower. Extra cable slack may need to be drawn through the sensor deployment pipes as the SDL500 is lowered.


SDL500 Cable Connections   SDL500 Cable Connections and Installation

Figure 7: SDL500 Cable Connections and Installation

Securing Buoy Lid

Install the buoy lid to the tower cap using the (3) 3/8”-16 bolts provided with the system. Include a washer and a lock washer between the bolt head and the lid (the washer sits under the lock washer). Tighten the bolts until the lock washers are flattened, then an additional 1/8” turn. Do not over-tighten the bolts to avoid stripping of the threading on the lid and cap.

Buoy Lid Installation

Figure 8: Buoy Lid Installation

Optional beacons or weather sensors to be mounted on the buoy lid can be installed once the lid is securely in place.

Setting Pipe Caps

PVC caps are included for additional protection of sensor pass-through tubes. Place a cap over each opening and secure with the provided bolts.


Pipe Cap on a Sensor Pass-through Tube

Figure 9: Pipe Cap on a Sensor Pass-through Tube

Connecting Bottom Sensors

On a CB-400S configuration, sensors may connect into Port 0 and Port D on the bottom of the RBP500 battery pack. The RBP500 acts as a pass-through, so the signal availability on enabled RBP500 ports is the same as is available on the SDL500. For example, the RS-232 and SDI-12 signals on the SDL500 Port P0 are also available on the RBP500 Port P0 when the UW-1P cable is attached.

Port P1 and Port T can be made available by connecting additional UW-1P cables between the battery pack and SDL500 within the buoy. Port A is unavailable on the bottom side of the buoy because it serves as a top-side battery vent. The SDL500 manual contains detailed information on selecting ports for sensor connections.

Double check that each UW plug and port have an O-ring installed. Missing O-rings will result in water intrusion and sensor failure. See Section 4.1.2 for more information.

 Sensor Connected to RBP500 Port P0

Figure 10: Sensor Connected to RBP500 Port P0


Deployment pipes, instrument cages and ballast weights can be added to CB-400 buoy systems. Deployment pipes and instrument cages provide options for secure mounting of sensors, and ballast weights can help to balance the buoy and prevent overturning.

Deployment Pipe

Deployment pipe extensions are easily fitted to the built-in sensor deployment pipes to provide extra protection for sensitive monitoring equipment. The 914 deployment pipe is a 4” Schedule 80 PVC pipe section that attaches to the sensor deployment pipes with a threaded adapter. The bottom of the 914 pipe is fitted with a stop bolt to keep sensors in place.

To attach a 914 deployment pipe, lay the buoy on its side and thread the deployment pipe into one of the three available pass-through sensor tubes. Take caution to avoid cross-threading of the adapter.  Also make sure the built-in deployment pipes do not rotate inside the buoy hull. The slotted top end must be properly aligned with the slot in the buoy tower to allow sensor cables to run from the tower to the deployment pipe assembly.

914 Deployment Pipe  CB-400S with 914 Deployment Pipe

Figure 11: CB-400S with 914 Deployment Pipe


Instrument Cage

The CB-400 buoy allows an instrument cage to be installed on the bottom. Sensors can be securely attached to the instrument cage. To install the cage, first remove the 1-3/4”-10 x 4” bolt, 1-3/4” lock washer and 1-3/4”-10 nut from the buoy frame.

Bolt on Buoy Frame

Figure 12: Bolt on Buoy Frame


Run the bolt downward through the buoy frame and top of the cage. Place the lock washer and nut onto the bolt.


Securing the Cage Assembly    Securing the Cage Assembly

Figure 13: Securing the Cage Assembly

Tighten securely with large crescent wrenches, and weld the connection to prevent the cage from coming loose in rough water.

Ballast Weight

Proper ballast weight is essential to prevent buoy overturning. Carefully consider the site-specific ballast requirements prior to deployment.

A 25 lb. ballast weight is available for installation to the bottom of the instrument cage for additional balance. Begin installation by inserting the 9-3/4” threaded rod section through the ballast weight and bottom of the buoy frame or instrument cage assembly.

Inserting the Threaded Rod

Figure 14: Inserting the Threaded Rod


On the bottom end of the rod, tighten a 1-3/4” eye nut with a 1-3/4” lock washer. Tighten the top end of the rod securely to the buoy frame or instrument cage with a 1-3/4”-10 nut and 1-3/4” lock washer. Weld the connections to prevent loosening in rough water.

Securing the Ballast Weight    Securing the Ballast Weight

Figure 15: Securing the Ballast Weight

REV: 13C12

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