Operating instructions

Appendix
108
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Glossary
Absolute encoder
Absolute encoders provide a distinctly coded numerical
value for each shaft position. The internal material
measure permits the read-out of an absolute measured
value after a supply voltage has been applied. A reference
run is not required.
Binary code
Code based on binary digits 0 and 1, which is used by
absolute encoders.
Changeable code frequency
Maximum number of measuring step changes per second.
Channel
Signal trace of the incremental rotary encoder.
Code progression
See Selection of count direction.
Fall time
Duration for an electrical signal to change from high to low
level.
Gray code
Code similar to binary code in which only one bit changes
from step to step. Higher data safety due to one-unit-
distance and cyclical code. This code has to be converted
into the binary code for data processing.
Gray excess code
This code is an extract of Gray code, which is used for the
representation of angular steps.
Example: 360 steps
In this case 9 bits are required, which corresponds to 512
steps. The extract of the code is symmetrical. It starts at
76 and ends at 436. The difference between the beginning
and end is 360 steps.
Incremental encoder
These encoders supply a frequency proportional to the
speed or a number of electrical pulses proportional to the
angle. A reference run should be carried out after a loss of
voltage.
LATCH
Storage function: By activating this input of the absolute
encoder the present value measured is "frozen". The
output will not change despite the shaft rotating.
If the input is deactivated, every new step measured is
output (transparent latch).
LSB
Least Significant Bit.
MSB
Most Significant Bit.
Multiturn
An absolute encoder which counts the number of shaft
revolutions of the shaft.
No load current
Power consumption of the encoder without load
connected.
Number of pulses
Resolution of the incremental rotary encoder. This
resolution indicates the number of pulses per revolution.
Offset
Value which is continuously added to a value measured.
Open Collector (OC)
Open collectors are differentiated according to OC-PNP
and OC-NPN output stages. The latter inverts the output
signals.
OC output stages are replaced by the push-pull output
stage in incremental and absolute encoders.
The inverted behavior of the OC/NPN output stage has to
be observed in absolute encoders.
Operating current
Indicates the permissible current load of the channel.
Operating temperature
Temperature range in which an encoder can be used, as
long as the values and tolerances mentioned in the data
sheet are maintained.
Operating voltage
Voltage supply of the encoder (U
b
).
Output frequency
The maximum signal frequency of the encoder, which
comprises the number of pulses and the rotation speed.
Overall resolution
Addition of single-turn and multi-turn resolutions. This is
expressed in number of bits.
Parity
Control bit to recognize failures in data transmission.
Phase position
Misalignment of the flanks of channels A and B of an
incremental rotary encoder.
PRESET 1
Reset of the control input. This action is used for
electronic adjustment of the absolute encoder output to
zero.
PRESET 2
Control input used to set the value measured to a
quarter of the single-turn resolution. This is used for
electronic adjustment of the absolute encoder. In case of
programmable absolute encoders, a value other than one
quarter of the single-turn resolution can be entered.
Push-pull output
The push-pull output is a combination of NPN and PNP
outputs.