Noland Engineering RS11 v3.0 Manual page 5

Engines using an inductive pickup require the connection in Figure 3b. The "ref" connection to rpm1(2)+ terminal may not
be needed unless there is no tach gauge present. Try connecting "rpm_+" to "ref" only if erratic readings exist without it be-
ing connected.
Regardless of the type of tach connection, you must determination the 'pulses/revolution' (ppr) of the engine. The only sim-
ple case is with ignition-sensed gasoline engines. The number of pulses per revolution (ppr) is usually one-half the number of
cylinders. So most 8-cylinder engines would have a ppr of '4'. If the engine is a diesel with an inductive pickup at the starter
flywheel, the ppr is equal to the number of teeth on the flywheel. Since few people actually know this number, you could
start with a value of '126' and then go up or down as necessary until the correct RPM is obtained.
If you have an alternator sensed tach signal, you have the toughest problem of all, since the ppr depends on the number of
poles in the alternator and the pulley diameter ratio between engine and alternator. The ppr value for this case is probably
between '12' and '36', so pick a number, send it to the RS11, and test.
Configuration Setup
The RS11 must be properly configured before it will send any useful data. The following preparation should be done before
configuration:
1. Decide which data you want to send (See Appendix A for help).
2. If RPM data is desired, determine engine pulses/rev (ppr).
3. For analog inputs, obtain 2 calibration points for each gauge/sensor.
4. Determine each analog "full-scale volts" range and set the internal jumpers.
5. Obtain a PC with Serial Port or USB-Serial Adapter.
If you can't do everything above, you can still configure the RS11 as much as possible and finish or update the configuration
later. Examples of calibrating analog sensors is given in Appendix C. A PC Setup Utility is available to simplify the RS11
configuration (see Appendix D).
Multiple RS11's
Installing multiple RS11's is particularly useful if you want more analog inputs than a single RS11 can provide. Each RS11
is assigned a unique Instance id during configuration by the user. An example is shown in Figure 4, where the Port side RS11
is given Instance='0'and the Starboard side RS11 is set to Instance='1'. Also, each RS11 must be configured as if it is only
connected to a single engine (see Appendix B).
Figure 4.