01.99 12 Functional Descriptions
12.11.2 ENDAT absolute encoder (SW 5.2 and higher)
12.11.2 ENDAT absolute encoder (SW 5.2 and higher)
Relevant machine data and alarms
• NC-MD 1264* Grid spacing/EnDat measuring step for linear scale
• NC MD 1804* bit 0 Symmetrical traversing range for ENDAT absolute encoder
• NC MD 1808* bit 0 Axis with absolute encoder
• NC-MD 1808* bit 1 Value range extension of absolute offset (MD 396*)
• NC-MD 1808* bit 2 Absolute encoder counting method opposite direction
• NC-MD 1808* bit 3 Absolute offset valid (MD 396*)
• NC-MD 1808* bit 6 Singleturn absolute encoder present
• NC MD 1820* bit 2 First measuring system with external zero mark
• Drive MD 1011.3 Configuration actual-value acquisition, motor measuring system,
absolute encoder with EnDat interface
• Drive MD 1030.3 Configuration actual-value acquisition, direct measuring system,
absolute encoder with EnDat interface
• Alarm 1040* Absolute encoder defective
12.11.2.1 Function features
The ENDAT encoder system is an encoder with an absolute encoder section and an
incremental encoder section.
The control requests the encoder absolute value from the encoder after every POWER ON or
deselection of ”Parking” and then calculates the machine absolute position. After that, the
control uses only the incremental encoder section with amplified sine/cosine output signals.
To determine the absolute information several binary-coded scale tracks are evaluated. With
the EQN 1325, the tracks are on several gear-coupled discs and on the linear scale with the
linear encoder LC 181.
Encoder key data:

R

otary absolute encoder HEIDENHAIN EQN 1325
Max. number of revolutions: 15.000 rpm
Max. sampling frequency: 500 kHz at 6 dB
Increments of the disk: 2048
Detectable number of revolutions: 4096
Activation precision: Depending on encoder resolution and position
controller resolution
Error information: 8 bits
Encoder key data: Linear absolute encoder HEIDENHAIN LC 181
Max. traversing speed: 40 m/min
Measuring lengths: 240 mm to 3040 mm
Measuring system resolution: 0.5/0.1/0.01 µm
Activation precision: Depending on encoder resolution and position
controller resolution
Error information: 8 bits
The max. number of encoder revolutions is:
• ± 2048 rev for linear axis
• 0 to + 4096 rev for rotary axis
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50
12–81
SINUMERIK 840C (IA)