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4.1.2.4.3
Errors Occurring when Configuring the Transmission Mode
Invalid configurations are listed below:
Problem
Mismatch of the
transmission rate
Duplex mode
mismatch
Mismatch using
autonegotiation
4.1.2.5
Important Terms
Data security
If an internal network (Intranet) is to be connected to the public network
(e.g., the Internet) then data security is an extremely important aspect.
Undesired access can be prevented by a Firewall.
Firewalls can be implemented in software or network components. They are
interconnected in a similar way to routers as a switching element between
Intranets and the public network. Firewalls are able to limit or completely
block all access to the other networks, depending on the access direction,
the service used and the authenticity of the network user.
Real-time ability
Transmission above the fieldbus system level generally involves relatively
large data quantities. The permissible delay times may also be relatively
long (0.1...10 seconds).
However, real-time behavior within the fieldbus system level is required for
ETHERNET in industry.
In ETHERNET it is possible to meet the real-time requirements by
restricting the bus traffic (< 10 %), by using a master-slave principle, or also
by implementing a switch instead of a hub.
MODBUS/TCP is a master/slave protocol in which the slaves only respond
to commands from the master. When only one master is used, data traffic
over the network can be controlled and collisions avoided.
WAGO-I/O-SYSTEM 750
PROFINET IO
Cause
Occurs when configuring one
link partner with 10 Mbit/s
and the other one with 100
Mbit/s.
Occurs when one link partner
is running in full-duplex and
the other in half-duplex mode.
Occurs when one link partner
is running in auto-negotiation
mode and the other one is
using a static configuration of
the transmission mode in full-
duplex operation.
Fieldbus Communication
ETHERNET
Symptoms
Link failure
Faulty or discarded data packets as
well as collisions on the medium.
The link partner, which is in
autonegotiation mode, determines the
network speed via the parallel
detection procedure and sets the duplex
mode to half-duplex. If the device is
operating in full-duplex mode with
static configuration, a duplex mode
mismatch will occur (see above).
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