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17.10.11
6.4. Input and output data
Module "Encoder data 32 Bit IO" is utilized for cyclic transmission of 4 byte encoder input data and 4 byte
encoder output data.
Input data (position value)
Encoder input data transmission to the control is performed cyclic by a consistent 32-bit, right-aligned data
word in binary code. To read the position the PLC software should access the parameterized input data
address using a double word.
31
0
Position
Encoder position (right-aligned)
Output data (preset value)
There is cyclic and consistent output data transmission from control to encoder. The output data may serve to
set the encoder to a defined position value within the parameterized total sensing range.
31
0
Preset
Preset (right-aligned). Preset operation is started by bit31
Bit 31: Preset
6.5. Preset
function
The preset function in the encoder is triggered by the PLC using bit 31 which is set in the output data. The
encoder position is set to the preset value (bit 30...0). Bit 31 should remain set for at least 10ms to be
recognized by the encoder. Afterwards time by principle does not matter since only a change in bit status
from „0“ to „1“ will be evaluated. We recommend however to clear the bit after completion in order to provide
the original status for the next preset operation.
For optimum alignment of mechanical position to preset we recommend to set the preset value during
encoder standstill, but it may also do during encoder operation for inferior requirements.
It is mandatory to parameterize the required resolution or code sequence (cw/ccw) prior to performing the
preset operation.
Upon performing a preset operation an internal offset is calculated and stored non-volatile in the Flash
memory to make sure the encoder will be at the same position again after power-off and power on. Although
the Flash provides 100.000 writing cycles, frequent software or event-triggered setting operations may
consume even this capacity what has to be considered in the control software configuration.
Note:
Any alteration of the total measuring range during encoder re-parameterization will implicate clearing the
internal preset-offset value. This however has no effect in practice since in this case the position is lost
anyway.
