Emerson P/N 400361-00 manual Home to Sensor then Marker

Velocity

Home Velocity

Home Offset

Home Accel Home Decel

Time

Home Initiate

Encoder Marker

Figure 34: \Home to Marker Profile (Specified Offset)

5.3.2 Home to Sensor

The Home to Sensor profile acts much like the Home to Marker profile, but instead of using the Encoder Marker as a reference, an external sensor mounted to the machine is used as the reference. In a Home to Sensor routine, the motor accelerates to the Home Velocity. The motor continues at the Home Velocity until the external sensor activates. Once this sensor activates, the motor immediately decelerates to a stop, or continues for a specified offset distance before stopping. Figures 35 and 36 show examples of the Home to Sensor profile, with calculated offset and specified offset respectively.

Velocity

Home Velocity

Home Accel Home Decel

Time

Home Initiate

External Sensor

Figure 35: Home to Sensor Profile (Calculated Offset)

Velocity

Home Velocity

Home Offset

Home Accel Home Decel

Time

Home Initiate

External Sensor

Figure 36: Home to Sensor Profile (Specified Offset)

5.3.3 Home to Sensor then Marker

The Home to Sensor then Marker profile is a combination of the two home types described above. Because in many applications the load will be more than one revolution away from the desired home position, a Home to Marker cannot be used because the marker activates once every revolution of the motor. Therefore, an external sensor is mounted on the machine to determine the home position. The SM-EZMotion module allows the user to home first to the external sensor, followed by a home to the next marker pulse. The Home to Sensor then Marker combines the accuracy of homing to the encoder marker with the flexibility of homing to an external sensor.

The Home to Sensor then Marker routine begins by accelerating up to the Home Velocity. The motor then continues at the Home Velocity until the external sensor activates. After the sensor activates, the motor continues at the Home Velocity until the next rising edge of the encoder marker is detected. Once the encoder marker activates, the motor either begins to decelerate immediately, or continues for a specified offset distance before stopping. Figures 37 and 38 show examples of the Home to Sensor then Marker profile, with calculated offset and specified offset respectively.

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