Control Techniques Nidec SI-EtherCAT User Manual page 118

The copy of the data to ma OPT_SYNC is an internal signal used for synchronisation purposes on
drives that support synchronisation.
OPT_SYNC occurs every 250 µs and can be synchronised with the EtherCAT network event
SYNC0 (which occurs at a rate dependent on network cycle time configured in the master). For
example, if the network cycle time is 1 ms. Four OPT_SYNC events will occur per SYNC0 event.
With one of the four OPT_SYNC events aligning with the SYNC0 event.
Data arriving from the Master causes the SM2 event to occur. The relationship of this event relative
to SYNC0 is governed by the master, but there should only be one SM2 event per SYNC0 cycle
period.
The copy of the data to mapped objects, controlled by this object, therefore can only take place
after the SM2 event. For example, in a 1 ms cycle with the SM2 occurring 30 % through the cycle,
the copy can only take place in either the 2
selected for the copy.
Typically, a value of '0' means the copy is scheduled to happen ~80 % through an OPT_SYNC
period; a value of '1' means a copy is scheduled to happen ~10 % through an OPT_SYNC period
and a value of '2' means a copy is scheduled to happen ~40 % through an OPT_SYNC period.
Note: these are approximate figures which will vary based on load, etc.
It should be noted, objects listed below, will take effect on the current or next SYNC0 event. If
0x3006:01 is set to the value of 1 (critical task) and the copy occurs at the OPT_SYNC aligned with
SYNC0 the copy takes place first and then the action applied based on this new value.
Although not recommended to change the default value unless necessary, the reasons for
adjusting from the default are:
• Avoid skew issues with parameter that are read by applications modules such as the SI-
Application family of modules and written by EtherCAT. SI-Applications module may be
configured to read parameters in the POS task which overlaps with the EtherCAT post
and pre-critical task.
• If the Master sends PDO data too late in the cycle for data to be handled in the pre-critical
task (the default). Although the shift offset should be adjusted in the first instance.
• If the master sends PDO data close to the point at which the copy takes place causes
data jitter issues. Although the shift offset should be adjusted in the first instance.
The data copy margin i.e. when a copy occurs related to SM2 event; can be observed by
monitoring the different values seen for parameter S.09.024.
The default values have been carefully selected, so the advice is not to change the default values
unless necessary.
Table 8-2 Objects that take effect in Pre-Critical event just before Sync0 event
Object / Subindex
0x60B2
0x6071
Table 8-3 Objects that take effect on SYNC0 event
Object / Subindex
0x60C1:01
0x607A
0x60FF
0x60B1
118
nd rd
or 3 OPT_SYNC cycle depending on which task is
Description
CiA402 Object Torque Offset - CSP, CSV, CST, and IP
Description
CiA402 Interpolation Data Record - IP only
CiA402 Target position - CSP only
CiA402 Target Velocity - CSV only
CiA402 Velocity Offset - CSV only
SI-EtherCAT User Guide