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Programming Your Application
690+ Series Frequency Inverter
Functional Description
It is intended that homing be used to bring the motor to reset from a low speed (10%) over a
relatively small distance (1 revolution). To achieve this the input should be connected to
Reference :: Speed Demand and the output to Setpoint Scale :: Input, this will override the
reference ramp.
Position Error is the distance in encoder pulses between the current position and Target position.
The homing distance is the stopping distance in encoder pulses.
Input
Speed
Calculator
X
Gain
Encoder Fbk
Position
Calculator
Enable
Decel Limit
Output
Error
Deceleration
Max Speed
Correction Limit
Done
Error Count
Encoder Lines
Possible Causes of Homing Errors
Take the example of lift (elevator) with the following parameters
Motor:
100% Speed = 1500 RPM
5000 line encoder.
Gearbox 18:1 @ 2.5m/s)
Pulley 650mm diameter @ 2.5 m/s 1 revolution = 110 mm
How far does the car travel between the detection of the homing sensor and the drive seeing the
ENABLE command?
It will be assumed that the drive will be travelling relatively slowly when it receives the home
command 1.5Hz = 0.75 RPM = 0.0825 mm / ms.
Typically the worst case levelling error will therefore be:
0.08 * (cycle time of lift cont cycle time of the vector drive)
= 0.08 * (10+5)
= 1.2mm.
Parameter Descriptions
ERROR
Range: FALSE / TRUE
Set TRUE if the maximum deceleration rate exceeded. Set FALSE if the block is not enabled.
ERROR COUNT
Range:
_.
This diagnostic is only valid in closed loop mode and shows the actual position error in encoder
counts. It is this error that is used to correct for positional errors in the speed setpoint generation.
DONE
Range: FALSE / TRUE
Set TRUE when the position has been reached or the output is at zero in open loop operation.
DECELERATION
Range:
_.xx
A diagnostic showing the actual deceleration used during the current / last home operation.
