Devolo G3-PLC Modem 500k, Руководство пользователя

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Configuration
devolo G3-PLC Modem 500k
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ceived, the data are sent on the serial interface and received responses are sent back as
UDP packets to the device that provided the most recently received UDP packet.
If data are received on the serial interface before a TCP connection has been
established or a UDP packet received, the data are discarded.
Prerequisites
Serial over IP can be used if the transfer protocol places minimal requirements on the
latency (perhaps several seconds) and the average data rate is less than the data rate of
approximately 50 kbps that can be achieved over G3-PLC. The feasible data rate drops
when transmitting many small packets.
If only cables are used, a continuous bidirectional transmission with a maximum
19,200 bps or a unidirectional transmission with a maximum 38,400 bps and a latency
of less than 1 second are possible. Higher data rates require corresponding breaks in
the data stream. For a "request/response" protocol, breaks are created solely by the la-
tency added through G3-PLC.
Example : Packets of 100 bytes are sent at 115,200 bps and the device waits for a re-
sponse of similar size. Taking various delays into account, a response would be re-
ceived after approximately 150-200 ms. The delay may be even longer for the first
packet.
Using cables connected through multiple devices increase the latency and decreases
the data rate. Considering three serial connections over PLC with six devices compared
to exclusive use, less than one third of the effective data rate would be available per
connection and the latency would be more than three times higher. This is due to po-
tential retransmission caused by data collisions.