Conditions - Siemens SIMATIC S5 Equipment Manual

General Function Description

1.8.2 Conditions

Incremental encoder:
1. The zero mark of the encoder and the preliminary contact define the end value of the rotary
axis. The encoder must be selected in accordance with the rotary axis requirements, or the zero
mark and the preliminary contact must be transferred to the 1P 241 accordingly.
Example: Desired area O to 359 (360 positions)
The zero mark with the preliminary contact appears exactly with pulse 360
(i.e., 359 is followed by the actual value O).
2. The preliminary contact, required for synchronizing of incremental encoders, and the zero mark
must be active at the zero position at each revolution. This means that in case of continuous
conveyors, the application of the respective prelimina~ contact is also required when the en-
coder crosses zero. This is one reason why absolute encoders are used for continuous con-
veyors. Another reason is that often no reference point traversing can be realized with a continu-
ous conveyor.
Absolute encoders:
The encoder end value defines the end value of the rotary axis.
This means that the encoder must be selected in accordance with the rotary axis requirements or
that a programmable encoder must be used.
Desired area Oto511
Example:
An encoder with512 position resolution is selected.
1 – 20
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
R 02/92