Connections (Point-To-Point Connections) - Siemens Simatic PG 740 Manual

Starting Up the PG 740
3.6
Point-to-Point
Connection
3
Suggestions for
Configuring TTY
(20 mA) Interfaces
Rules
3-12
PG 740 Connections (Point-To-Point Connections)
In this section, you will learn how to connect your PG 740 to a programming
device or programmable controller over a point-to-point connection.
You establish a point-to-point connection by connecting the PG 740 to
another programming device or a programmable controller via
a V.24 connection
a TTY connection
Reliable data transfer depends on several factors. The data transfer rate you
can achieve depends on the distance, the type of cable, the type of interface
and any interference present.
You can reduce interference by choosing the right transmission cable and
connecting it properly, and observing the following guidelines.
Use a shielded cable with a low line resistance (< 130
capacitance (< 90 pF/m). Twisted-pair cables enhance immunity to noise
due to inductance. A low surge impedance results in reduced voltage
excursions and shorter charge reversal times. The surge impedance
decreases with increasing conductor cross-section for the same length of
cable.
The shorter the transmission link, the higher the maximum possible data
transfer rate.
If there is an active sender and an active receiver at the same end of the
transmission link, the sequence of access priority to the transmission
circuit must be taken into account in order to achieve the longest possible
transmission link.
Signal lines and power lines must not be run together. Signal lines must
be installed as far away as possible from strong interference sources
(400 V three-phase power cables, for example).
The active TTY interface with 12 V no-load voltage has been tested on a
1000 m (3300 ft.) long cable at a transmission rate of 9600 bps in a
normal noisy environment. If a shielded LiYCY 5x1x0.14 is used, reliable
transmission is possible over a distance of up to 1000 m (3300 ft.). The
AS511 protocol (only one transmitter at a time) was used for testing.
Note
The contaminating field of the interference source decreases exponentially
with the distance.
/ km) and low
Programming Device PG 740
C79000-G7076-C742-01