5
Operation
Festo – EXCM-30/-40-...-PF-EN – 1603 – English
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5.5
Control via Ethernet (CVE)
Note
The CVE interface is not real-time capable. Control of the controller through Ethernet
requires a risk estimation by the user:
Only use the CVE function in applications in which the lack of real-time capability
cannot pose risks.
5.5.1
General
With the function “Control via Ethernet” (CVE), the controller can be controlled via the Ethernet inter
face. The controller is pre-parameterised for this purpose with the Festo Configuration Tool (FCT). It is
possible to start and jog both homing and positioning jobs through CVE.
The controller can be actuated through the CVE interface in the record selection and direct mode oper
ating modes.
5.5.2
Communication
The basis for CVE communication is TCP/IP data transfer. The controller acts as the server in this setup,
while the PC application acts as the client, i.e. the PC application always sends a request to the control
ler, which sends back a response (client-server principle).
The TCP connection is typically built up once and then remains in place as long as communication with
the controller is required.
The TCP port used can be set via the FCT. The port number 49700 is set at the factory.
Communication with the controller takes place via the CVE protocol. This must be imple
mented in the PC application. Knowledge of programming TCP/IP applications is required
for this purpose.
CVE communication takes place via the CVE protocol (
è
5.5.3 CVE protocol), whereby control data are
written to CVE objects and status data are read out of CVE objects.
In the record selection mode, a record parameterised via the FCT is selected through CVE objects and
started.
In the direct mode, the target position in the direction of the X- and Y-axis as well as the speed, acceler
ation and jerk values are written directly to CVE objects. The information on whether positioning should
take place absolutely or relative to the last setpoint position as well as the start of the direct applica
tion is also realised by writing to CVE objects.