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PSI-MODEM-SHDSL/ETH, TC ETH EXTENDER
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PHOENIX CONTACT 104273_en_01
3.3 DSL technology
In contrast to an analog permanent line modem, DSL (Digital Subscriber Line) uses a
greater frequency range, which enables a data rate that is several times higher. With DSL,
the modulation process is used on different carrier frequencies, in this way enabling robust
modulation that is much more resistant to external sources of electro-magnetic interference.
The DSL technology used here is the SHDSL variant. A greater range can be realized with
SHDSL than with other DSL technologies. In addition, the bandwidth for the up and down
stream is equally large (symmetrical data transmission). For this reason, SHDSL is well
suited for industrial applications. SHDSL is standardized in the ITU-T G.991.2. Further tech-
nical information can be found there.
Ethernet extenders with SHDSL technology are ideal for retrofitting a system, because the
extenders can be used with the system's existing wiring.
3.3.1 Determining the data rate
A precise prediction of the maximum possible data rate is difficult in practice as many pa-
rameters play a role:
– Cable type
– Structure
– Diameter
– Capacity
– Shielding
– Installation of the cable
– Number of crossovers
– Influence of cables laid parallel
– EMC influences of neighboring devices on the communication line
If installing new cables, we recommend using shielded twisted pair cables.
An initial estimation of the possible data rate is possible using the (Figure 3-6) diagram or
via the SHDSL calculator software. The software can be downloaded free of charge at
phoenixcontact.net/products .
The actual data rate can be determined with a practical test. Phoenix Contact provides test
kits with two Ethernet extenders, which can be used to test the path under realistic condi-
tions.