Specification Servo
One
6
2.4 Parameterization of polarity and phase
Correct configuration of the polarity and phase is important for error-free operation of
the SSI interface. The polarity setting is determined by the resting level of the SSI clock
line. If the clock line rests at a Low level, parameter TOPT_SSI_Polarity (
P 2803
) should
be set to False. True means the clock level rests at High level. The phase indicates when
a new bit is placed on the data line and when the bit is then evaluated. If parameter
TOPT_SSI_Phase (
P 2804
) is set to False, the data are always applied back to the resting
level at the edge. If the setting is True, the data are applied away from the resting level
at the edge.
Polarity
Phase
False
False
False
True
True
False
True
True
Daten
Table 2.4
Parameterization of polarity and phase
2.5 Suffixing a parity bit
A parity bit can optionally be suffixed after the user data. The parity bit is then trans-
ferred after the least significant bit (LSB). The parity bit is enabled by way of parameter
TOPT_SSI_ParityEnable (
P 2805
). The parity can be set either as "odd" or "even". This
can be selected by way of parameter TOPT_SSI_ParityType (
P 2805
).
2.6 Using synchronization
Where the SSI information is scanned at equidistant time intervals it is possible to
synchronize the control cycle of the ServoOne to the scan cycle. The synchronization
is executed to the first clock edge of a transfer. When using synchronized mode, it is
important that the read cycle of the control system is an integer multiple of the speed
control cycle. Synchronized scanning can be used to ensure that position values polled
at the equidistant time intervals can be transferred to the higher-level control system. If
multiple synchronized ServoOne units were scanned simultaneously, all actual position
values would be generated at the same time.
Synchronization is enabled by way of parameter TOPT_SSI_SyncUse (
P 2808
). Parameter
TOPT_SSI_InSync (
P 2809
) displays the synchronization status.
