Names and Functions of Parts
2-4
2.1.3 ESM (State Transition Diagram)
Init
Pre-Operational
Safe-Operational
Operational
(IP)
(PI)
(SI)
(SP)
(SO) (OS)
(PS)
(OP)
(OI)
Reference: Created by us based on "Operating principle of EtherCAT" issued by ETG
ESM state
(Abbr.)
SDO
communication
Send/Receive
PDO
communication
(S
M)
PDO
communication
(M
S)
Description
Init
Not available Not available Not available
The state that the
communication part is
being initialized and data
cannot be sent/received
using SDO (Mailbox) and
PDO.
Pre-Operational
(PreOP)
Available Not available Not available
The state that data can be
sent/received using SDO
(Mailbox).
Safe-Operational
(SafeOP)
Available Available Not available
The state that data can be
sent/received using SDO
(Mailbox) and data can be
sent (from slaves to
master) using PDO.
Operational
(OP)
Available Available Available
The state that data cannot
be sent/received using
SDO (Mailbox) and PDO.
(Note): S: Slave, M: Master
What is ESM (EtherCAT State Machine)?
• ESM shows the state of the communication determined as the specifications of EtherCAT.
• The state transition is performed between FP7 MC Unit and Servo Amplifier A6B/A5B, any
settings or programming by users are not required.
Confirmation method
• The state of ESM can be confirmed by the operation monitor LED "EC RUN" on the front
side of FP7 MC Unit.
• When communication is performed, "Operational (OP)" (EC RUN LED) is on, and the input
relay “X0 (Link establishment)" of FP7 MC Unit is on.