Process Data - Beckhoff EP3356-0022 Documentation

Commissioning/Configuration
Time stamp
See Notes on latency regarding [} 67] the time when the actual timestamp is acquired.
6.11

Process data

This section describes the individual PDOs and their content. A PDO (Process Data Object) is a unit on
cyclically transmitted process values. Such a unit can be an individual variable (e.g. the weight as a 32-bit
value) or a group/structure of variables. The individual PDOs can be activated or deactivated separately in
the TwinCAT System Manager. The "Process data" tab is used for this (visible only if the terminal/box is
selected on the left). A change in the composition of the process data in the TwinCAT System Manager
becomes effective only after restarting the EtherCAT system.
The EL/EP3356 can be used in 2 basic operating modes
• 1-channel strain gauge evaluation (strain gauge, balance beam, load cell): Here, both analog input
voltages are measured internally, they are calculated locally according to the internal settings in the
terminal/box and the resulting load value is output to the controller as a cyclic process value. The
terminal/box is to be regarded as a 1-channel terminal/box. The load value can be output as an integer
or as a float/real representation.
• 2-channel voltage measurement: Both analog input voltages are output directly as process values; no
load calculation takes place. The value and status information can be output for each channel.
The basic operating mode of the EL3356 terminal / EP3356 box is determined by the selection of the
process data (PDO).
EL/EP3356 and special versions
EL/EP3356, EL3356-0010 and EP3356-0022 have the same process data except. EL3356: no
mode switching in the ControlWord
Selection of process data
The process data of the EL/EP3356 are set up in the TwinCAT System Manager. The individual PDOs can
be activated or deactivated separately. The "Process data" tab is used for this (visible only if the terminal/box
is selected on the left).
92 Version: 1.1.0 EP3356-0022