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Terms and Definitions
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2. Terms and Definitions
The terms and definitions used in this guide are given below.
Term
Explanation and Definition
PDO communications
(Process Data Objects
communications)
PDO communications is used for constant data exchange
between a master and slaves. PDO data (i.e., I/O data that is
mapped to PDOs) that is allocated in advance is input and
output each EtherCAT process data communications cycle (i.e.,
the task period of primary periodic task). The NJ/NX-series
Machine Automation Controllers use PDO communications for
commands to refresh I/O data in a fixed control period, including
I/O data for slave units and the position control data for
servomotors. It is accessed from NJ/NX-series Machine
Automation Controllers in the following ways.
・
With device variables for EtherCAT slave I/O
・
With axis variables for a servo drive and encoder input slaves
to which an axis is assigned
SDO communications
(Service Data Objects
communications)
SDO communications is used to read and write specified slave
data from a master when required. The NJ/NX-series Machine
Automation Controllers use SDO communications for
commands to read and write data, such as for parameter
transfers, at specified times. The NJ/NX-series Machine
Automation Controllers can read/write the specified slave data,
such as parameters and error information, with the
EC_CoESDORead (Read CoE SDO) instruction or the
EC_CoESDOWrite (Write CoE SDO) instruction.
slave unit
A generic name for a device that performs EtherCAT
communications with an EtherCAT master. There are various
types of slave units such as servo drives that handle position
data and I/O terminals that handle bit signals.
node address
An address to identify a slave unit connected to EtherCAT.
ESI file
(EtherCAT slave information
file)
It contains information unique to EtherCAT slave units in XML
format. The ESI file can be loaded into Sysmac Studio, to
allocate EtherCAT slave process data and make other settings.
Summary of Contents for sysmac EtherCAT NJ101 Series
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