Noland Engineering RS11 v3.0 Manual page 3

RPM (Tach) Connection
The RS11 is designed to support the most commonly used tachometer
sensors. Some sensors, such as inductive pickups, produce low level
differential signals which the RS11 detects directly with its sensitive
differential inputs. For other signals, such as ignition pulses or alter-
nator tach outputs, the RS11 has a 2.5V reference ('ref') which is used
as a stable threshold for detecting these often noisy signals.
In general, 2-wire tach signals (where one wire is NOT 'Ground' ) use
both the "rpm+/rpm-" inputs directly. Single wire tach signals, such as
ignition pulses or alternator tach outputs, connect only to the "rpm+"
terminal and have the "rpm-" terminal connected to "ref". The RS11
"rpm+/-" inputs are very high impedance so they do not load the tach
signal. Connecting either of the "rpm-" terminals to "GND" will usu-
ally result in erroneous RPM readings or no RPM at all. The next
section (INSTALLATION: Tach Hookup) contains more details re-
garding tach hookup and calibration.
CANbus Interface
The CANbus connector (Micro 'C') provides the RS11 DC power and data interface. It is normally connected to an active
network through a Tee. The RS11 has no other means of obtaining power besides this connector. If required, you can bench
power the RS11 with a CANbus DC injector cable, which is useful for configuration, reprogramming etc. Sending messages,
however, will only occur if it is connected to an active bus. The RS11 flashes a green LED when it sends messages and a red
LED if errors or received messages occur.
Resest Connection: A 2-pin connector on the side of the RS11allows for external shutdown or reset of the unit. This is par-
ticularly useful if the RS11 must be shut down when the engine is stopped. A switch or relay closure can serve as the shut-
down interface.
Serial (PC) Interface: The Serial Interface is intended for direct connection to a PC COM Port. It has several important func-
tions, which include:
1. RS11 setup (RPM divider, Analog scale factors, data selection, etc.)
2. Monitoring data output and diagnosing errors on a PC.
3. Reprogramming and Software upgrades.
If your PC has no Serial Port, you can connect this to a USB-Serial adapter and perform all operations through the resulting
Virtual COM Port. Configuration can be done manually, but it is better to use the supplied Setup Utility (see Appendix D).
3. Installation
Installation of the RS11 requires a CANbus (or another CANbus instrument) and access to your engine gauges or sensors. A
PC with a Serial (COM) Port is also needed for initial configuration/calibration. If your PC has no Serial Port, you need a
USB-Serial adapter to provide a "Virtual COM Port".
CANbus connection: A CANbus interface provides both power and data to/from the RS11. The unit will not operate without
DC power from the bus interface. Connection to the bus is generally made with a 'Tee' from the main bus backbone. Once
connected, the unit will immediately claim its address and begin sending messages to the bus, if enabled.
When connecting the RS11 to other CANbus instruments, a 120 ohm termination is usually needed somewhere on the bus.
For small networks that only have a few devices and relatively short cable lengths, a single termination is adequate. For
buses with many instruments and or very long cable lengths, it is better to place a termination at or near each end of the bus.
Figure 2. Analog
full-scale
voltage settings