AKD EtherCAT | 5 Appendix
5.3.50 Object 3496h: Fieldbus synchronization parameters
This set of objects is used to set or read parameters for the fieldbus synchronization used in
the interpolated position mode (7) and the cyclic-modes 8 etc. The synchronization between
a fieldbus master and the AKD is similar in all the supported fieldbus systems.
The AKD internal 16[kHz] interrupt function is responsible for calling the PLL function. This
PLL function is called once per fieldbus cycle (set by object 60C2 sub 1 and 2).If the fieldbus
sample period is for example 1[ms], the PLL code is called every 16th time of the 16[kHz]
IRQ of the AKD.
Once in a fieldbus sample the SYNC-telegram must arrive, which resets a PLL counter in the
Drive. After some time the already mentioned PLL function is called and reads back the time
from that PLL counter.
Depending on the measured time the PLL function extends (in case that the measured time is
too low) or lowers (in case that the measured time is too high) the sample time of the upcom-
ing 16[kHz] tasks for one fieldbus sample by a selectable value (object 3496 sub 4) in order to
move the PLL function closer to the expected distance (object 3496 sub 1).
Beside the objects mentioned here the parameter FBUS.SAMPLEPERIOD is important,
which is set by object 60C2 sub 1 and 2.This setting is required in order to share the fieldbus
sample time with the slave. This information is e.g. needed for being able to call the AKD
internal PLL function once per fieldbus sample.
Index
3496h
Name
FBUS synchronization parameters
Object code
Array
Data type
UNSIGNED32
Category
optional
Subindex
0
Description
highest sub-index supported
Category
mandatory
Access
R/O
PDO mapping
not possible
Value range
0x4
Default value
0x4
Subindex
1
Description
FBUS.SYNCDIST
Category
optional
Access
R/W
PDO mapping
not possible
Value range
UNSIGNED32
Default value
320000 [ns]
Sub 1 is the expected time distance in nano seconds between clearing the PLL counter and
calling the PLL function.
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Kollmorgen | kdn.kollmorgen.com | October 2017
