Siemens simatic et 200s Operating Instructions Manual page 200

1PosSSI/Digital
5.5 Fundamentals of Controlled Positioning Using Rapid/Creep Feed
Definitions
Term
Operating range
Switchover difference
Switchover point
Switch-off difference
Switch-off point
Start position
Target XE "Target"
Linear axis XE "Linear axis"
Rotary axis
Minus direction
Plus direction
200
Explanation
Defines the range, which you set for a particular task by means of the hardware limit
switches.
In addition, the operating range is also restricted by the range covered by the SSI
encoder.
You enter the encoder range in the parameters for:
Number of increments
•
Number of rotations
•
Encoder range = number of rotations * number of increments
Maximum operating range:
Linear axis - max. 0 to (encoder range -1)
•
Rotary axis from 0 to (encoder range - 1)
•
Defines the distance from the destination at which the drive is switched over from rapid
feed to creep feed.
Defines the position at which the drive is switched over from rapid feed to creep feed.
Defines the distance from the destination at which the drive is switched off.
If the switch-off difference ≥ the switchover difference, there is no switchover point. There
is no change from rapid feed to creep feed.
Defines the position at which the drive is switched off.
The 1PosSSI/Digital reports the end of the run at this point.
Defines the position of the drive within the operating range from which the run is started.
If the start position is within the switch-off difference, the drive is not triggered. The
1PosSSI/Digital reports the end of the run at this point.
If the start position is within the switchover difference, the run is only executed in creep
feed mode.
Defines the absolute or relative position of the axis approached during positioning.
The destination is the position to be reached on an axis during a run.
In the case of an absolute run, you specify the destination directly by means of your
control program.
In the case of a relative run, the destination is calculated from the start position and the
path specified in the control program.
If you want to find out how accurately you have reached the destination, you have to
compare the actual value with the position specified.
Defines the axis type with a limited operating range.
It is limited by the following:
The encoder range
•
The numeric range that can be represented (0 to 16 777 215 increments)
•
The hardware limit switch
•
Defines the axis type with an infinite operating range.
This includes resetting the axis position to 0 after one rotation (assigned parameter
encoder range).
If the drive moves in the minus direction, the actual value displayed is decreased.
If the drive moves in the plus direction, the actual value displayed is increased.
Operating Instructions, 05/2007, A5E00124871-04
ET 200S Positioning