Amax-4800 Series Features; Ethercat Free-Run And Distributed Clock (Dc) Modes - Advantech AMAX-4800 Series User Manual

1.2

AMAX-4800 Series Features

The AMAX-4800 series comprises industrial EtherCAT slave modules equipped with
the EtherCAT protocol. The modules' compact size and integrated DIN rail mount kit
enable easy installation in cabinets. Euro-type pluggable terminal blocks and LED
indicators assist users with system setup and maintenance. All modules are pro-
tected by an isolation circuit, making them suitable for demanding industrial applica-
tions.
1.2.1

EtherCAT Free-Run and Distributed Clock (DC) Modes

EtherCAT telegrams are sent by the EtherCAT master to all connected EtherCAT
slaves, which perform continually synchronous/asynchronous sequences of calcula-
tions and/or data copying actions.
EtherCAT has two data transfer modes – Free Run mode and DC mode.
Free Run Mode
In Free Run mode, the local cycle is triggered via a local timer interrupt, and the cycle
time can be modified by the master (optional) to change the timer interrupt. The local
cycle operates independent of the communication cycle, and the slave refreshes I/O
data asynchronous to the master.
DC Mode
In DC mode, the slave refreshes I/O data in synchronization with the master's com-
munication cycle. A mechanism known as a distributed clock (DC) is applied to timing
signals generated independent of the communication cycle for precise timing require-
ments. The DC is shared to synchronize the master and the slaves. Interruptions
(Sync0) are generated in the slaves at precise intervals based on this clock. Each
slave executes I/O processing at this exact time. This means that all EtherCAT
devices can share the same EtherCAT system time (global time base) for synchroni-
zation.
AMAX-4800 User Manual
Figure 1.6 Distributed Clock Unit Interfaces
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