134 Fieldbus Communication
WAGO-I/O-SYSTEM 750
750-375 PROFINET IO advanced Fieldbus Coupler
Manual
Version 1.1.0
With addressing to the MAC address, an IO device first receives a device name as
part of the configuration (station naming) using DCP. The IO device stores this
unique device name in non-volatile memory.
The device name enables the IO controller to allocate the station proxy with an IP
address, subnet mask and standard gateway for establishing productive data
exchange when starting the system.
Alternatively a device name instance can predefined in the WAGO fieldbus
coupler PROFINET IO via the DIP switch.
11.2.5
PROFINET Communication Principle
11.2.5.1 Data Traffic
Various types of data traffic are used for PROFINET communication.
•
Cyclic real-time data traffic (RT/IRT)
In cyclic data exchange, the I/O data of the individual I/O modules
(modules/submodules) takes a proportionate share (subslots) in the provider
and consumer telegram. The I/O data is transmitted unacknowledged
between the IO controllers and associated IO devices, but each subslot
contains additional status information that provides information on the
validity of the information transferred. If cyclic message traffic fails,
connection monitoring of both devices ensures that the established
application relationship is terminated.
•
Acyclic real-time data traffic (RTA)
Events such as fault conditions on I/O module peripherals, e.g.
"undervoltage" or "short circuit", user limits exceeded or failure of the
process data connection and transferred per associated alarm between the IO
controllers and associated IO devices.
•
Data cross traffic
Cyclic data transmission from one provider to several nodes is implemented
as data cross traffic. With PROFINET IO, this type of transmission is called
Multicast Communication Relation (MCR).
•
Reading and writing data sets (records)
Demand data, e.g. I/O module parameterizations, device identification and
maintenance information, as well as extended channel and module
diagnostics, are transferred via the RPC protocol over the UDP channel.
11.2.5.2 Communication Connection
To establish a communication link between the IO controller and an IO device,
the communication paths must be established.
They are established during system start-up by the IO controller based on the
configuration data received from the configuration software. All data exchange is
embedded in a "Application Relationship" (AR). A precisely specified
relationship (AR) is established between the IO controller and IO device.
