Haltech S4 Hall Effect Sensor - Manual (Page 6)

The S4 Hall Effect Sensor
The S4 sensor which is identified by a grey cable gland operates in the following
way:
As a south pole passes the sensor face the signal in the secondary (PIN D) channel is
switched to a low state. As a north pole passes the sensor a low state will only occur
on the primary channel (PIN C).
The set-up for this sensor is similar to the S3 except that one extra magnet is required
as well as the orientation being changed. The north pole of the magnet is used to
generate the main trigger while a south pole is used to generate the home or
synchronisation pulse.
Typical set -ups - S4
4 cylinder / 2 rotor engine
For a four cylinder 3 magnets are required in total. Two north poles positioned exactly
180° apart while a south pole needs to trigger the sensor before the trigger for
cylinder No 1. Th e positioning of the magnet for cylinder one is done the same way
as the for the S3 making sure the north pole is triggering the sensor at approximately
75° BTDC.
FIGURE 4: TYPICAL 4 CYLINDER/ 2 ROTOR APPLICATION