Siemens SIMATIC S5-90U System Manual page 500

Function Modules
Example:
A rotary incremental position encoder produces 1000 pulses per revolution.
The spindle has a pitch of 50 mm/revolution. The position encoder therefore produces 1000 pulses
for a traversing path of 50mm (1 revolution).
The resolution of the encoder is therefore 50 mm/1000 pulses.
The counter can handle up to 65536 pulses. With the above resolution, the following traversing
ranges are obtained:
Table 16-4. Example for a Traversing Range
Pulse evaluation
Traversing range
Distance travelled/
pulse
Loading Setpoints
In the STEP 5 program, two setpoints can be transferred to the module. These setpoints must lie
between -32768 and +32767.
The acceptance of the setpoints by the module depends on whether the "setpoint 1 (setpoint 2)
reached" bit has been set in the diagnostic byte.
If the bit is not set, which means the existing setpoint is not reached or not exceeded, the new
setpoint is immediately accepted and is immediately valid.
If the bit is set, which means the existing setpoint is reached or exceeded, the new setpoint is not
valid until a positive edge occurs at the enable input.
If you do not specify a setpoint, a setpoint of "0" applies.
Synchronization of the Actual Value Detection (Reference Point Approach)
The synchronization of the actual value detection is necessary after "power-up" and after a counter
overflow.
Synchronization performs the following functions.
• The count (actual value) is set to "0" and
• The SYNC bit (bit 0 in the diagnostic bit) is set after "power-up"
or
• The overflow bit (bit 3 in the diagnostic byte) is reset after an overflow
16-32
Single
3.25 m (10.7 ft.) 1.625 m (5.3 ft.)
50 µm
Double Quadruple
0.81 m (2.7 ft.)
50 µm 50 µm
S5-90U/S5-95U
EWA 4NEB 812 6115-02b