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Control via Ethernet (CVE)
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Festo – GDCP-CMMO-ST-EA-SY-EN – 2017-05c – English
B.2
Explanation of increments
Encoder increments
The CMMO operates in the field of drive control (e.g. in a path generator) with encoder increments (EINC).
Interface increments
In contrast, so-called interface increments (SINC) are used at all user interfaces and in the field of in
ternal data management. This enables rounding errors to be avoided when reading and writing values.
Conversion factors
The relationship between interface increments (SINC) and encoder increments (EINC) is established via
the following conversion factors:
– Transmission ratio of the gear unit
– Feed constant
Size of a SINC
Interface increments are at first dimensionless, i.e, they have no defined unit or size. The unit, i.e. the
size of an SINC, is specified in objects #218 “Unit of measurement” and #217 “Power of ten”:
During parameterisation in FCT you can use commonly used units for length specifica
tions, such as millimetres or inches. You do not need any interface increments here.
Parameterise the drive completely in FCT and then read objects #218 “Unit of measure
ment” and #217 “Power of ten”.
Example:
#218 = 1, i.e. Metre
#217 = –6, i.e. 10
–6
è
1 mm = 1000 SINC
