EtherCAT State Machine  

The EtherCAT State Machine (ESM) is required on all EtherCAT devices. The ESM in general

• defines 5 communication states of the slave device
  • Init, Pre-Operational, Safe-Operational, Operational
  • Bootstrap is an optional state for firmware upload
• specifies initialization and error handling of the slave device
• identifies the current communication relationship between the master and slave device
  • requested and current state are accessed through the AL Control and AL Status registers

The ESM states can be transitioned as shown

Init State

• No communication to the application layer is allowed
• master only has communication to the data link registers (slave device eeprom, addressing, etc)

Pre-Operational State

• Mailbox (SDO) communication to the application layer is available
• No Process Data (PDO) communication.
• PDO register mapping should be completed. Transition to Safe-Operation will configure mapping.

Safe-Operational State

• Mailbox (SDO) communication to the application layer is available
• Slave output (tx) Process Data (PDO) communication is evaluated

Operational State

• All communication is commenced and valid

Bootstrap State

• The bootstrap state is used when updating EtherCAT firmware. 

Explicit Device ID

General Description

The use of EtherCAT Device identification is to identify an EtherCAT slave explicitly. This is necessary for the following use cases:

• Hot Connect applications 
  Within some applications it might be useful to connect or disconnect parts of the network. In this case the master must have the possibility to identify which part of the network is available.
• Prevention against cable swapping 
  If at least two identical devices are used in one application it might be necessary to prevent the mix-up of these devices by cable swapping. Example Scenario: Within a machining center there might be two identical drives to work in X and Y direction. To avoid that the drives receive wrong process data, for example after a device replacement, an explicit identification of the devices can be used.

The Device Identification value can be used optionally for unique addressing.

Rotary Selectors

The CM1-E uses 2 rotary selectors on the side of the motor to set the ID. These use hexadecimal values to set the range from 0-255. The values are set as follows

ID Range Usage

The following ID range is permissible

Configured Station Alias

For backwards compatibility with certain master controllers the Configured Station Alias Register 0x0012 may be used. The following conditions exist:

PDO Timing

The CM1-E slave will accept a number of PDO rates. The rate is auto-detected and no additional setup is required on the slave.

Accepted rates are

1. 1000μs (1ms)
2. 500μs
3. 250μs
4. 200μs

The detected rate can be read in object 0xFE00:1.

PDO Mappings 

The Cool Muscle EtherCAT slave has a few static PDO mapping options. It does not use dynamic mapping.

• The RxPDO is the PDO received by the motor/slave device
• The TxPDO is the PDO transmitted by the motor/slave device

Position units are in encoder counts (pulses). There are 50,000 encoder counts per revolution. 

The following mappings are available.

Dynamic Switching of mode

This mapping is useful as a generic mapping. The master can run in any of the available modes as well as switch dynamically between them. The PDO also offers a lot of feedback information for diagnostics.

RxPDO - 0x1600

TxPDO - 0x1A00

CSP Mode

This mapping is useful when a minimum amount of data wants to be transferred using CSP mode.

RxPDO - 0x1601

TxPDO - 0x1A01

CSV Mode

This mapping is useful when a minimum amount of data wants to be transferred using CSP mode.

RxPDO - 0x1602

TxPDO - 0x1A02

Profile Mode

This mapping is useful when profile position or profile velocity mode is used.

RxPDO - 0x1603

TxPDO - 0x1A03