Position Decoding And Resolution - Siemens SIMATIC S5 Manual

Machine Data, Modes and Traversing Programs
5.1.2

Position Decoding and Resolution

Unit of measure
You may use one of the following units of measure on the IP 266 for all positional
specifications:
• Metric system with 0.001 mm as base unit
• Inch with 0.001 inches as base unit
• Degree with 0.001 degrees as base unit
A base unit is the smallest unit that may be entered as the unit of measure.
The specified unit of measure also applies to
• speeds
• acceleration rates and
• encoder resolution
If you have chosen [deg] as the unit of measure, the speed is specified in
[deg/min].
Encoder type
You may connect the following types of encoder to the IP 266:
• Encoders with symmetrical 5 V output signals
• Encoders with asymmetrical 24 V output signals
The encoder type is specified in the machine data's "Encoder type" parameter.
In order to ensure precise measuring of the drive's current position, you must use
an encoder whose resolution meets with your specific requirements.
Two items of data are needed to compute the resolution:
• Travel per encoder revolution and
• Pulses per encoder revolution
Travel per encoder revolution
The "travel per encoder revolution" depends on your drive system, and should
take accurately into account all transmission elements, such as couplings and
gears, which are located between the motor and the incremental encoder.
5-4
IP 266
EWA 4NEB 812 6057-02