Siemens SIPART DR22 Manual page 148

2 Installation
2.2 Electrical Connection
D Connection of the serial interface
For V.28 point-to-point connections of the SES, a 9-pin socket strip for round cables is avail-
able.
SIPART DR 19/21/22/24
serial
interface
6DR2803-8C
Figure 2-2 Plug for serial interface
9-pin socket strip for round cables (screw terminal)
Recommended cable:
4-core unshielded round cable
D Zero volt system
The SIPART DR22 controllers only have a 0V conductor (ground, GND) on the process side
which is output double at terminals 1/1 and 1/2 of the standard controller. If these GND con-
nections are not sufficient, additional proprietary terminals can be snapped onto the DIN rail
on the power pack. The controller uses a common reference for both inputs and outputs, all
process signals are referred to this point.
The reference line is also connected to vacant terminal modules. These may only be used if
practically no current flows through this connection (see e.g. fig. 2-13, page 151, I 4L).
The power supply connection is electrically isolated from the process signals. In systems
with unmeshed control circuits, the SIPART DR22s need not be interconnected. In meshed
control circuits the GND connections of all controllers must be fed singly to a common ter-
mination or the continuous GND rail with a large cross-section. This common termination
may be connected with the system's PE conductor at one point.
Since in analog signal exchange between the devices, only currents 0/4 to 20 mA are used
and these are evaluated as a four-pole measurement (differential amplifiers with electronic
potential isolation), voltage drops on the M-conductor are not interpreted as errors (see fig.
2-26, page 159 to fig. 2-32).
The signal-to-noise ratio on digital signals is so great that voltage dips on the GND rail can
be ignored.
146
-D39
9 pol.
7 4
C73451-A347-D39
JE-LiYY 4x1x0.5 BdSi
SIPART DR22 6DR2210
C79000-G7476-C154-03
Manual
remote system
V. 28
point-to-point
≤ 10 m