JVL Industri Elektronik A/S - User Manual - Ethernet for MAC and MIS motors 39
3.2 Protocol specifications
Sync0 pulse
The distributed clock allows multiple devices on the network to share a common time
reference, but doesn't itself provide any real functional synchronization.
Additional hardware is provided on the DC enabled slave devices, which allows a pulse
to be generated on the slaves at a fixed period.
This pulse, known as the Sync0 pulse, is used by the slave device to synchronize its inter-
nal functions to the network.
The master is responsible for configuring the Sync0 pulse on each slave. Typically, the
master finds a sync period which is compatible with all slave devices, and configures the
Sync0 signal on all devices to occur simultaneously.
The acceptable sync periods for each slave device can be found in the documentation
provided by each device manufacturer. JVL MAC400+ servo motors have an internal po
-
sition loop with an update rate of 1kHz (1ms) - (alternatively 1.3 or 2.6mS), when used
with the MAC00-ECx.
For the synchronization to work, it is needed that the Sync0 period used is an integer
multiple of the 1ms position loop update rate. The JVL EtherCAT implementation sup
-
ports 1 and 2 ms sync0 pulse.The MIS/MIL motor do not have any internal position loop,
but nevertheless synchronizes its internal position update to the Sync0 pulse.
Once the Sync0 signal is configured by the master to a multiple of the motor's servo pe-
riod, the motor will adjust its internal loop to align the start of a servo period with the
Sync0 signal.
Since the master typically configures the Sync0 signals of multiple drives on the network
to occur simultaneously, the result is simultaneous servo updates on multiple devices.
Synchronization specifications
When using synchronization the servo motor has to synchronize to the Distributed Clock
of the network. This is done with a PLL circuit which takes a little time to settle.
But when settled it has a maximum jitter of ±1μs.
Settle time of PLL:
Cycle time Typical settle time Max. settle time
1ms 2.4s 5s
2ms 2.6s 5s
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