3 General functions
3.2 Functions dependent on the mode of operation
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OZD Profi G12D... ATEX 1 V. 03 07/2014
In the operating mode “electrical channel without seg-
ment monitoring, connected RS 485 bus segments are
not monitored. Interferences of the electrical segment
affect the entire network.
Kindly observe the installation information in chapter 5.6
“Connect electrical bus cables” on page 37.
Following functions are available only for the optical
channels. Activation of the functions is independent of
the set operating mode.
Kindly refer to the following chapters for detailed infor-
mation.
Line monitoring via Echo
The repeater enables active monitoring of the connected
optical paths for interruptions of the fibre optic cable
through the “send echo”, “monitor echo” and “suppress
echo” functions.
Send echo
If the repeater receives a telegram through any channel,
the same is send to all other channels. If the receiver is
an optical channel, the repeater sends the telegram back
to the related optical transmitter.
Monitor echo
If the repeater transmits a telegram - no echo! – to an
optical channel, the Repeater expects an echo. If echo
does not arrive after a specified time, echo monit oring
error is signalled with a red LED belonging to a channel.
Suppress echo
The rele vant receiver is separated from he remaining
channels from the start of transmission of the telegram
up to complete reception of the echo.
Segmentation
If an echo monitoring error or distortion occurs on an
optical channel, the repeater assumes a line fault and
blocks this channel for user data. The connected fieldbus
subnetwork is thus segmented (detached). Due to this
segmentation, the repeater on the opposite side of fibre
optic is also segmented.
Both repeaters connected to the segmented fieldbus
subnetwork transmit test telegrams to the segmented
channel. Both repeaters can check the status of the field-
bus subnetwork through these test telegrams to be
received regularly.
Segmentation is automatically cancelled as soon as both
the repeaters detect the segmented fieldbus subnetwork
with the help of test telegrams.
If all active bus stations in a previously active network are
switched off, the repeaters are segmented in cycles for
checking the fibre optic paths for neighbouring modules.
In the absence of telegram traffic but intact fibre optic
paths, the channel LEDs of the optical channels blink yel-
low in cycles.
