Noland Engineering RS11 v3.0 Manual page 4

Avoid assembling long buses with lots of multi-branching nodes. Instead, try to assemble a single backbone with each device
directly connected to it with a Tee. Put a 120 ohm termination some- where along the backbone, or if very long, use two termina-
tions, one at each end.
Serial Connection
A serial 9-pin connector is provided with each RS11 for connection to a PC. It is primarily intended for configuration of the unit,
but may be left in place for data monitoring, if desired. If your PC has no Serial Port, a USB-Serial adapter will be needed. The
Serial Interface will not function unless the RS11 is connected to either a powered bus or a Power Injection cable.
If you do not wish to leave the Serial cable connected, put it safely away for future use. If you ever need to reconfigure the RS11
or update its software, you will need this, or a similar, cable.
Analog Gauge connections
Connections to the analog inputs (A1-A4) are usually made at the "sense" or 'S' terminals of existing gauges. Alternatively, the
connections can be made directly at the engine sensor(s), if preferred. Keep in mind that the RS11 does not provide DC power to
sensors, since that is normally done by the vessel gauges.
Note: The RS11 uses CANbus "Ground" as an analog '0V' reference. This may be adequate for most installations,
but others may need to connect the "GND" terminal of the RS11 to an engine ground for stable analog readings.
All analog inputs (A1-A4) must have their appropriate full-scale voltage set by jumpers within the unit. Figure 2 shows the full-
scale settings available. The specific jumper settings of each analog input depend entirely on what each input is measuring. For
example, if an analog input is measuring the voltage of a 12 volt marine battery, the full-scale voltage should be set to 15V. For
measuring a 24 volt battery, the full-scale voltage should be set to 30V. All jumpers are factory set to 15V and may be left this
way for most 12V systems. For 24V systems, you may need to use the 30V setting. Sensors which produce only a few volts of
maximum output should use the '5V' setting.
Tach hookup
There are several RPM (tach) connection alternatives. Most gasoline engines derive their tach signal from ignition pulses where
a fixed number of pulses represent one revolution of the engine. The signal is often available on the back of the Tachometer, or a
wire from an Engine Control Unit (ECU), or it can be obtained directly from the Ignition Coil. For these types of engines, the
tach signal should be connected to RS11 'rpm 1(2)+' terminal and the rpm1(2)-' terminal is connected to 'ref '. Port side or sin-
gle engine installations should use 'rpm1+/-' while starboard side engines should use 'rpm2+/-' (see Figure 3a). The 'ref ' termi-
nal is a stable 2.5V signal, which acts as a switching threshold for tach pulses. Most gasoline engine tach signals and alternator
tach ouputs will require the connection "ref" into the "rpm1(2) -" terminal(s). This hookup makes the RS11 more immune to
noise on the Tach signal.
a) Ignition or Alternator Tach Hookup
Diesel engines use another scheme for RPM sensing since they have no ignition system. Some diesels use an inductive
pickup sensor at the flywheel, while others use a special output from the alternator. For the flywheel sensor, the number of
teeth on the flywheel must be known, whereas alternator-sensed RPM requires knowledge of the number poles in the alter-
nator and the alternator/engine pulley ratio. Alternator sensed RPM is most often connected as shown in Figure 3a.
Figure 3. RS11 Typical Tach Connections
b) Inductive Pickup Tach Hookup (diesel)