Emerson SI-Universal User Manual page 88

(1x.091) = 1, then the encoder simulation output only follows the changes of source position. At
power-up, on device Initialization and a marker event no additional pulses are produced to give the
absolute position of the device related to zero position. The encoder simulation output marker is not
synchronised to the source marker.
If a source other than P1 Position (1x.029) is selected Encoder Simulation Incremental Mode
Select (1x.091) has no effect and the encoder simulation system always operates in absolute
mode.
2: Ratio
The encoder simulation is derived in the same way as described previously for Encoder Simulation
Mode (1x.088) = 1 (i.e. lines per rev mode), except that different parameters are used to set up the
system giving more flexibility as shown below.
With the default settings ( Encoder Simulation Numerator (1x.093) = 65536, Encoder Simulation
Denominator (1x.094) = 65536 and Encoder Simulation Output Roll-over Limit (1x.095) = 65535)
the output produces a state change each time the source parameter changes by one. The
numerator and denominator can be changed to provide a different ratio between the source and the
output. Output markers are produced each time the output counter is zero and the counters are
synchronised in the same way as for lines per rev mode.
It is possible to control the roll-over limit of the output counter and hence the rate at which output
markers are produced using Encoder Simulation Output Roll-over Limit (1x.095). For example if the
ratio is set to 1024/ 65536 and the roll-over limit is 1023 then one output marker is produced for
every 1024 lines of output incremental signals. If the roll-over limit is changed to 512, then two
output markers are produced for every 1024 lines of output incremental signals.
3: SSI
In this mode the B output becomes the clock input and the A output is the data output. If the source
position is the P1 position feedback interface, the data from the position feedback interface is
transferred to the SSI output register once per sample period as defined by the Encoder Simulation
Sample Period (1x.087).
Figure 7-6 illustrates SSI data alignment
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SI-Universal Encoder User Guide
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