Connecting The Pg 720 To Other Simatic S5 Units - Siemens SIMATIC PG 720 Manual

Installing the PG 720
4.7

Connecting the PG 720 to other SIMATIC S5 Units

Point-To-Point
Link
Suggestions for
Configuring TTY
Interfaces (20 mA)
Rules
4
4-16
In this section, you will learn how to connect your PG 720 to a programming
device or programmable control using a point-to-point link.
You can establish a point-to-point link by connecting the PG 720 to another
programming device or a programmable controller using
a V.24 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 DC resistance (130
and low capacitance (90 pF/m) (about 27 pF/ft). Twisted-pair cables are
less susceptible to noise and interference. A low DC resistance results in
reduced voltage excursions and shorter charge reversal times. The DC
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
1000 m (3300 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 1000 m (3300 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.
/ km) (about 40 kft)
PG 720 Programming Device
C79000-G7076-C720-02