Festo CPX-FB38, Электронное руководство

Страница: 63 / 120

2. Commissioning
2−27
Festo P.BE−CPX−FB38−EN en 0804NH
2.4.2 Addressing and data access (data objects)
Addressing
Addressing the individual modules requires the supervisory
controller: The EtherCAT master determines the position of
the EtherCAT devices within the network. Thereby, block−
oriented addressing is applied (in contrast to block−oriented
addressing of other field bus systems).
The controller uses the following for local addressing:
the physical position of the devices within the EtherCAT
network (Auto Increment Address)
an independent EtherCAT device address
(EtherCAT address).
If required, the EtherCAT address can be changed.
The global addressing is supported by a Field bus Memory
Management Unit (FMMU).
Note
You will find CPX specific information regarding the
addressing in the section 2.3.
Data access (data objects)
EtherCAT internal data is retrieved based on protocol−specific
data objects (according to the fieldbus protocol CANopen).
EtherCAT devices have an object directory which makes all
important slave parameters accessible in a standardized
manner. An EtherCAT system is configured mainly by access
to the object directory of the individual slaves.
The access mechanism is provided by means of Service Data
Objects (SDO).