Specifications

40
Schneider Electric
Review
Networks
A network is defined by its:
b Topology (bus, ring, star, tree, mesh, etc.)
b Physical limits (length, speed, number of subscribers, etc.)
b Type of physical medium used (cable, optical fibre, radio waves, etc.)
b Type of network access (random, master-slave, token ring, with or without error
management, etc.)
b Transmission modes (synchronous/asynchronous, in packets, serial/parallel,
NRZ/Manchester coding, etc.)
b Protocol (TCP/IP, FIP, MODBUS, etc.).
Systems
Bauds and bits per second
One important parameter to be considered when choosing a cable is bandwidth.
Bandwidth is related to modulation speed expressed in Bauds.
Bauds are often mistakenly expressed in bits per second.
This parameter is of greatest interest to the user. The two are often confused
because their valence is generally 1.
A valence of 2 indicates that the throughput is doubled for the same communication
speed.
Definition : The purpose of a
communications network is to link at least
two devices in order to exchange data (ex.:
Ethernet network).
Definition : A system brings together a
number of different entities that function
independently but are connected to each
other (in a network) in order to participate in
an overall function.
Definition : A baud corresponds to a
number of electrical states per second..
Definition : The throughput or number of
data bits transmitted in one second on the
network is expressed in bits per second.
Definition : Valence is the ratio between
throughput in bits/s and speed in bauds.
E70510
10
0001101100
1
10
0
010
2.5 V
5 V
U
2.5 V
5 V
t
t
U
Guide to Integration
Modbus / Jbus