Siemens SINUMERIK 840C - Manual (Page 868)

09.01 12 Functional Descriptions
12.11.2 ENDAT absolute encoder (SW 5.2 and higher)
12.11.3.3 First start-up
Initial state
Initial state standard MD
MD 1808*, bit 3=0
Absolute offset not valid
MD 1808*, bit 7=0 No range extension
MD 1808*, bit 0=0 No absolute encoder exists
MD 3944*=0 Rough encoder position=0, no overflow
MD 3940*=0 Gear denominator=0
Note:
The initial state is equivalent to the standard data setting. If other parameter settings are
active, bit 3 in MD 1808* must be set to 0 before continuing with step 1 (i.e.: absolute offset
not valid).
Step 1:
Set MD 1808*, bit 0 and bit 7 to 1, with rotary axes the gear denominator is parameterized in
NC MD 3940* and an NCK Power On is performed.
Step 2:
The drives equipped with an absolute encoder must now enter the closed-loop control (control
e.g. via a small traversing movement). After that, the absolute encoder must be adjusted. The
absolute offset is set correctly in MD 396* after the axis has been measured and declared valid
by setting MD 1808*, bit 3=1.
Step 3:
With linear axes especially, it is advisable to approach a known position (e.g. a visible mark)
and then back up the NC MD at this point. This MD file can then be used at this position after
data loss in the SRAM instead of a file saved shortly before.
Note:
After each start-up, the service display should be checked for any number of overflows. After
the first start-up, a value between -1 and 1 (usually 0) should be displayed here, in the case of
endlessly turning rotary axes this value should be between 0 and 1.
The initial start-up process needs to be repeated whenever the service display shows
unreasonably high values. For this, parameterize the following machine data:
MD 1808*, bit 0=1 Absolute encoder present
MD 1808*, bit 3=0 Absolute offset not valid
MD 1808*, bit 7=1 Initialize encoder coarse position
Subsequently, initiate NCK Power On and continue with step 2.
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 12–93
SINUMERIK 840C (IA)