Siemens SINUMERIK 840C - Manual (Page 849)

12 Functional Descriptions 08.96
12.11 Absolute encoder
12.11 Absolute encoder
12.11.1 SIPOS absolute encoder up to SW 4
12.11.1.1 Functions
The SIPOS encoder system consists of a multiturn absolute encoder which functions
absolutely when switched on and incrementally during operation.
To reduce the dimensions of the encoder, part of the encoder electronics are located on a
submodule, the absolute submodule. The absolute submodule is plugged on the HMS
measuring circuit module.
After each POWER ON, the control requests the encoder absolute value from the absolute
encoder and then calculates the absolute position of the machine. The absolute encoder then
functions in exactly the same way as a standard incremental encoder with amplified sine and
cosine output signals.
The coded disc information (cyclic absolute) and the value from the battery backed tachometer
are taken to determine the absolute information. The buffer battery is located on the absolute
submodule and stores the information for up to three axes.
Encoder key data:
Max. sampling frequency: 500 kHz
Increments on disc: 2500
Revolution information:: 16 bits
Accuracy on POWER ON: 1 µ m at a 10 mm spindle pitch (10000 incr./rev )
Error information: 8 bits
Battery back-up: 5800 hours for 3 encoders, built in battery monitoring
Even during operation, the back-up battery level is checked every 10 minutes and a message
displayed on the control if a fault occurs.
If an additional back-up battery is installed in the encoder, the measuring circuit module and
the encoder cable can be replaced without loss of absolute information. This battery back-up
lasts for up to 5 hours.
Since 1 October 1994, the SIPOS encoder has been available only
as a spare part for existing installations.
The EnDat absolute encoder must be used for new applications.
12.11.1.2 Hardware requirements
The absolute encoder submodule is plugged onto the HMS measuring circuit in the same way
as conventional servo command modules.
The absolute encoder submodule is equipped with its own type 8096 processor which
determines the values for up to 3 axes.
The absolute encoder back-up battery which is also for up to 3 axes, is located on the
absolute submodule.
The SIPOS absolute encoder can only be used in conjunction with the
HMS measuring circuit module (high-resolution measuring system).
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SINUMERIK 840C (IA)