Coe Interface - Beckhoff EL6731 Documentation

Basics communication
Boot
In the Boot state the slave firmware can be updated. The Boot state can only be reached via the Init state.
In the Boot state mailbox communication via the file access over EtherCAT (FoE) protocol is possible, but no
other mailbox communication and no process data communication.
4.4

CoE Interface

General description
The CoE interface (CAN application protocol over EtherCAT)) is used for parameter management of
EtherCAT devices. EtherCAT slaves or the EtherCAT master manage fixed (read only) or variable
parameters which they require for operation, diagnostics or commissioning.
CoE parameters are arranged in a table hierarchy. In principle, the user has read access via the fieldbus.
The EtherCAT master (TwinCAT System Manager) can access the local CoE lists of the slaves via
EtherCAT in read or write mode, depending on the attributes.
Different CoE parameter types are possible, including string (text), integer numbers, Boolean values or larger
byte fields. They can be used to describe a wide range of features. Examples of such parameters include
manufacturer ID, serial number, process data settings, device name, calibration values for analog
measurement or passwords.
The order is specified in 2 levels via hexadecimal numbering: (main)index, followed by subindex. The value
ranges are
• Index: 0x0000 ...0xFFFF (0...65535
• SubIndex: 0x00...0xFF (0...255
A parameter localized in this way is normally written as 0x8010:07, with preceding "x" to identify the
hexadecimal numerical range and a colon between index and subindex.
The relevant ranges for EtherCAT fieldbus users are:
• 0x1000: This is where fixed identity information for the device is stored, including name, manufacturer,
serial number etc., plus information about the current and available process data configurations.
• 0x8000: This is where the operational and functional parameters for all channels are stored, such as
filter settings or output frequency.
Other important ranges are:
• 0x4000: here are the channel parameters for some EtherCAT devices. Historically, this was the first
parameter area before the 0x8000 area was introduced. EtherCAT devices that were previously
equipped with parameters in 0x4000 and changed to 0x8000 support both ranges for compatibility
reasons and mirror internally.
• 0x6000: Input PDOs ("input" from the perspective of the EtherCAT master)
• 0x7000: Output PDOs ("output" from the perspective of the EtherCAT master)
Availability
Not every EtherCAT device must have a CoE list. Simple I/O modules without dedicated processor
usually have no variable parameters and therefore no CoE list.
If a device has a CoE list, it is shown in the TwinCAT System Manager as a separate tab with a listing of the
elements:
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Version: 2.8 EL6731