4-13
PG 720 P Programming Device
C79000-G7076-C721-02
4.7
Connecting the PG 720 to other SIMATIC S5 Units
In this section, you will learn how to connect your PG 720 to a programming
device or S5 programmable logic controller using a point-to-point
connection.
You can establish a point-to-point connection by connecting the PG 720 to
another programming device or a programmable logic controller using
An RS-232 connection
A TTY connection
To ensure reliable data transfer, several factors must be taken into account.
You can reduce interference by choosing the right transmission cable and
connecting it properly, and by observing the following guidelines:
Use a shielded cable with a low line resistance (130
/ km) (about 40
kft) and low capacitance (< 90 pF/m) (about 27 pF/ft). Twisted-pair cables
are less susceptible to noise and interference. A low line resistance results
in reduced voltage excursions and shorter charge reversal times. The line
resistance 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 run together. Signal lines must be
installed as far away as possible from sources of strong interference (for
example, 400 V 3-phase power cables).
The active TTY interface with a 12 V no-load voltage has been tested on a
100 m (1100 ft) long cable at a transmission rate of 9600 bps in an
environment with normal levels of noise (field strength < 3 V/m or 1 V/ft).
If a shielded LiYCY 5 x 1 x 0.14 shielded cable is used, reliable transmission
is possible over a distance of up to 100 m (1100 ft). The AS511 protocol (only
one transmitter at a time) was used for testing.
Note
The interference field of the source decreases exponentially with the
distance.
Point-To-Point
Connection
Configuring
Interfaces with
Line Current
(TTY, 20 mA)
Rules
Installing and Operating the PG 720
