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Tab 'EtherCAT Master - General' Permalink

Object: EtherCAT Master

The tab is used for the configuration of the basic settings for the EtherCAT Master. The basic settings are preset from the device description file.

Settings of the configuration parameters

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The auto-configuration mode (“Autoconfig master/slaves” option) is selected by default and is adequate for standard applications. If the mode is not selected, then all configuration settings for the master and the slave(s) have to be done manually. Expert knowledge is required to do this. The auto-configuration mode option has to be switched off to configure slave-to-slave communication.

“Autoconfig master/slaves”

_cds_icon_option_activated The main part of the master and slave configuration is done automatically, based on the device description file and implicit calculations. The dialog for the FMMU/Sync settings is not available.

Even if this option of the master is selected, an expert mode can be enabled explicitly for each individual slave, which allows for manual editing of the automatically generated process data configuration.

Table 447: “EtherCAT NIC Settings”

“Target address (MAC)”

MAC address of the device in the EtherCAT network that is to receive the telegrams.

Options

  • “Broadcast”: A “Target address (MAC)” does not have to be specified.

  • “Redundancy”: Enabled when the bus is constructed in a ring topology and redundancy is to be supported. With this function, the EtherCAT network remains functional even in the case of a broken cable. When this function is enabled, the parameters have to be defined in the “Redundancy EtherCAT NIC Settings” area.

“Source address (MAC)”

MAC address of the controller (target system) or network name (name of the adapter or PLC (target system))

“Network name ”

Name or MAC of the network, depending on which of the following options is selected:

“Select network by MAC”

_cds_icon_option_activated: The network is specified by the MAC ID. Then the project cannot be used on another device because each network adapter has a unique MAC ID.

“Select network by name”

_cds_icon_option_activated: Network is identified by the network name and the project is device-independent.

“Scan”

Scans the network for the MAC IDs or names of the target devices that are currently available.

Table 448: “Redundancy EtherCAT NIC Settings”

These settings are displayed only when the “Redundancy” option is selected. Here the parameters of the additional device are defined according to the description for “EtherCAT NIC Settings”.

Table 449: “Distributed Clock”

“Cycle time (µs)”

Time span after which a new data telegram is dispatched on the bus. When the “Distributed Clock” function is enabled in the slave, the master cycle time specified here is transferred to the slave clocks. As a result, a precise synchronization of the data exchange can be achieved. This is particularly important when spatially distributed processes require simultaneous actions. An example of a simultaneous action is applications in which multiple axes have to execute coordinated movements at the same time. A very precise, network-wide time base with a jitter of considerably less than 1 microsecond can be achieved in this way.

“Sync offset”

Parameter for setting the delay time between the DC time base of the EtherCAT Slave and the cycle start of the PLC. The default value is 20%. This time is active at the same time for all slaves with DC. An offset of 20% means that the timer interrupt in the EtherCAT Slave takes place 20% before the next IEC cycle.

This means in the case of

  • ‎FrameAtTaskStart‎ = ‎FALSE‎ when the EtherCAT data is sent at the end of the PLC cycle:

    The PLC cycle may require 80% of the bus cycle time minus the delay time in the runtime, and this without the master no longer placing the current process data on the bus in time (assuming that the EtherCAT Slave expects the new data exactly with the sync interrupt).

  • ‎FrameAtTaskStart‎ = ‎TRUE‎ (default value when using CODESYS SoftMotion):

    For the controller program, nearly 100% of the cycle is always available. Here the “Sync offset” determines only when the EtherCAT data of the master is exchanged to and from the slaves relative to the time base of the EtherCAT Slave.

If DC is active at the corresponding slave, then the default settings come from the respective ESI file. The device manufacturer can define additional offsets here in the form of the Shift time for both Sync 0 and Sync 1 timer interrupts. When the expert setting is enabled at the slave, these times can be changed manually. The Shift time is entered into the register 0x990 as an additional start time. A positive value means that the start takes place later and therefore the sync interrupt is executed later.

IMPORTANT It must be prevented at all costs that the sync interrupt takes place near the time of the IEC cycle because otherwise no data can exist for one cycle and devices go into synchronization error. Both offsets from the master and the individual offset of each slave have to be considered for this. With the normal setting of 20% offset for the master and 0% for the slaves, the jitter of the IEC cycle and the delays of the transmission timing by the system can be a maximum of +80% and –20%.

“Sync window monitoring”

_cds_icon_option_activated Synchronization of the slaves can be monitored.

“Sync window”

Time for “Sync window monitoring”. When the synchronization of all slaves is within this time window, the variable ‎xSyncInWindow‎ (‎IoDrvEthercat‎) is set to ‎TRUE‎, otherwise to ‎FALSE‎.

Table 450: “Options”

“Use LRW instead of LWR/LRD”

_cds_icon_option_activated Direct communication from slave to slave is possible. Combined read/write commands (LRW) are used instead of separate read commands (LRD) and write commands (LWR).

“Messages per task”

_cds_icon_option_activated Read and write commands (the handling of the input and output messages) can be controlled by means of various tasks.

“Automatically restart slaves”

_cds_icon_option_activated The master immediately attempts to restart the slaves in the case of a communication breakdown.

Table 451: “Master Settings”

These settings can be edited only when the “Autoconfig master/slaves” option is deactivated. Otherwise this is done automatically and they are not visible here.

“Image In Address”

First logical address of the first slave for input data

“Image Out Address”

First logical address of the first slave for output data