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

PDO Mappings 

The Cool Muscle EtherCAT slave uses dynamic switching between modes and as such there is a single fixed PDO configuration.

All position, speed and acceleration data reference units. Units are defined as encoder counts. There are 50,000 encoder counts per revolution of the motor.

RxPDO

The RxPDO is the PDO received by the motor/slave device

TxPDO

The TxPDO is the PDO transmitted by the motor/slave device