
58
SM-Universal Encoder Plus User Guide
www.controltechniques.com
Issue Number: 6
8
Advanced Operation
8.1
Serial communications
8.1.1
SinCos
Encoder Comms Resolution
Where encoder comms is used for initial setting of absolute position (SC.HiPEr or
SC.EndAt), the comms resolution in bits must be set correctly, either by the user in
Pr
x.11
or the Solutions Module automatically (see Pr
x.18
). The comms resolution may
be higher than the resolution of the sine waves per revolution.
Encoder Comms Baud Rate
The SinCos encoder comms baud rate is fixed at 9600 baud when using a Stegmann
Hiperface encoder (Pr
x.14
encoder comms baud rate has no effect.)
Any baud rate can be used when encoder comms is used with a SinCos encoder to
obtain the absolute position during initialisation, as long as this is within the encoder’s
specification.
Encoder Turns
When an encoder with comms is used, Pr
x.09
must contain the number of bits in the
comms message used to give the multi-turn information. For a single turn comms
encoder Pr
x.09
must be set to zero. It is possible for the drive to set up this parameter
automatically from information obtained from the encoder via Hiperface or EndAt
interfaces during auto configuration.
Encoder Position Check
If Pr
x.44
is set to one, position checking is disabled and encoder comms is available via
the transmit and receive registers. The transmission system can be used to
communicate with encoders provided the mode is SC.HiPEr or SC.EndAt as follows:
For both comms protocols more than one byte of data must be written to the transmit
register or read from the receive register during the transfer of one message. Bits 13-15
are used to indicate the following:
At power-up Pr
x.45
is initially zero, but is set to one when the encoder connected to the
Solutions Module has been initialised. The drive cannot be enabled until Pr
x.45
is one.
If the encoder power-supply is lost, or the encoder type Pr
x.15
is changed for an
encoder connected to a Solutions Module, and the encoder type is SC, SC.HiPEr,
SC.EndAt or EndAt the encoder will no longer be initialised.
When an encoder is no longer initialised Pr
x.45
is reset to zero and the drive cannot be
enabled.
The encoder may be re-initialised, provided the drive is not active, by setting Pr
3.47
to
one. Pr
3.47
is automatically reset to zero when the initialisation is complete.
NOTE