3
1. Functional description
1.1 GENERAL FUNCTIONS
Signal regeneration
The RH1-TP/FL processes the signal shape
and amplitude of the data received.
Retiming
In order to prevent jitter increasing over
several segments, the RH1-TP/FL retimes
the data to be transmitted.
Preamble regeneration
The RH1-TP/FL supplements lost preamble
bits from data received to 64 bits (incl. the
start of frame delimiter (SFD)).
Fragment extension
Collisions can cause short fragments to
occur. If the RH1-TP/FL receives a fragment,
this is supplemented to give the minimum
length of 96 bits. This ensures reliable colli-
sion detection by all network participants.
Collision handling
If the RH1-TP/FL detects a data collision, it
interrupts the transmission. For the
duration of the collision, the collided data
package is replaced by a jam signal to
ensure collision detection by the terminal
equipments.
Auto partitioning
Network failures can be caused by perma-
nent occupancy, interruptured lines, lack of
terminating resistors, damaged cable insu-
lation and frequent collisions due to electro-
magnetic interference. In order to protect
the network from such failures, the RH1-
TP/FL in this case separates the segment in
the receiving direction from the rest of the
network.
The RH1-TP/FL has this auto partitioning
function individually at each port. The other
ports can thus continue to be operated
without interference if one of the ports has
been auto partitioned. In the event of auto
partitioning, transmission continues into
the TP segment or the F/O line but reception
at this port is blocked.
With twisted pair, auto partitioning is activa-
ted if
– a data collision lasts longer than 105 µs or
– there are more than 64 consecutive data
collisions.
With F/O, auto partitioning becomes active
when
– a data collision lasts longer than 1.5 ms
(normal mode) or 0.2 ms (redundant
mode) or
– there are more than 64 (normal mode) or
16 (redundant mode) consecutive data
collisions.
Reconnection
The segment is reconnected to the network
as soon as a package with the minimum
length of 51 µs is received without collision
at the relevant port, i. e. when the segment
is working properly again.
When the redundant mode is active, packa-
ges >51 µs sent at a F/O port without collisi-
on also lead to reconnection.
Jabber control
Due to a defective transceiver or LAN con-
troller, for example, the network can be con-
tinuously occupied with data. To protect
against this, the RH1-TP/FL interrupts
reception
– at the affected TP or AUI port after 5.5 ms.
9.6 µs after the end of the error the auto
partitioning will be canceled.
(jabber lockup protection)
– at the relevant F/O port after 3.9 ms. 420
ms after the end of the error the auto par-
titioning will be canceled.
(Rx jabber)
1.2 SPECIFIC FUNCTIONS OF THE
TP INTERFACE
Link control
The RH1-TP/FL monitors the connected TP
line segments for short-circuit or interrupt
using idle signals during frame pauses in
accordance with IEEE standard 802.3
10BASE-T. The RH1-TP/FL does not transmit
any data in a TP segment from which it
does not receive an idle signals.
Note: A non-occupied interface is assessed
as a line interrupt. The TP line to terminal
equipment which is switched off is likewise
assessed as a line interrupt as the de-
energised transceiver cannot transmit idle
signals.
Auto polarity exchange
If the reception line pair is incorrectly
connected (RD+ and RD- switched) polarity
is automatically reversed.
1.3 SPECIFIC FUNCTIONS OF THE
F/O INTERFACE
Link control
The RH1-TP/FL monitors the connected F/O
lines for interrupts using idle signals during
frame pauses in accordance with IEEE stan-
dard 802.3 10BASE-FL. The RH1-TP/FL
transmits no data to an F/O line from which
it is receiving no idle signal.
Redundancy
In areas where data security has top priori-
ty, it is possible with the aid of the redun-
dancy function to bridge any failure of an
F/O line or RH1-TP/FL. To do so, a replace-
ment line is frequently routed in a different
cable run. In the event of a fault, there is an
automatic switch between the main line and
the replacement. A cross-link within the bus
structure creates a ring (see Fig. 6). If any
RH1-TP/FL link or RH1-TP/FL fails, every
other RH1-TP/FL can still be reached with
the aid of the redundant run.
Hirschmann Patent Frame Redundancy:
– EP 0403763 (Europe)
– NO 5.218.600 (USA)
1.4 DISPLAY ELEMENTS
Equipment status
The 4 LEDs on top provide information
about the status which affects the function
of the entire RH1-TP/FL.
P1 – Power 1
(green LED)
– lit: supply voltage 1 present
– lit not: – supply voltage 1 not present,
– hardware fault in RH1-TP/FL
P2 – Power 2
(green LED)
– lit: supply voltage 2 present
– lit not: – supply voltage 2 not present,
– hardware fault in RH1-TP/FL
DA – Data
(yellow LED)
– lit: RH1-TP/FL receiving data at at least
one interface
– lit not: – RH1-TP/FL not receiving data at
any interface,
– hardware fault in RH1-TP/FL
Depending on network load, the illuminati-
on of the LED can vary between a brief
lighting up to permanent illumination.
CD – Collision Detect
(red LED)
– lit: data collision detected at RH1-TP/FL
level
– lit not: – no data collision at RH1-TP/FL
level
Port Status
These groups of LEDs display port-related
information.
LS1 to LS3 - link status of the TP ports
(3 x green LED)
– lit:
RH1-TP/FL receiving idle signals
from TP segment,
– the TP segment connected is
working properly
– lit not: RH1-TP/FL is not receiving any idle
signals from TP segment,
– the assigned TP port is not
connected,
– the equipment connected is
switched off,
– the TP line is interrupted or
short-circuited
