Siemens SIMATIC S7-300 Module data User Manual

RS 485 Repeater
9.3 RS 485 Repeater in ungrounded and grounded operation
S7-300 Automation System Module data
9-4 Manual, 08/2006, A5E00105505-04
9.3 9.3 RS 485 Repeater in ungrounded and grounded operation
Grounded or ungrounded
The RS 485 Repeater is ...
● Grounded, if all other nodes on the segment are also operated on ground potential
● ungrounded, if all other nodes in the segment are operated on ungrounded potential
Note
Bus segment 1 is grounded if you connect a PG to the PG/OP socket of the RS 485
Repeater. The segment is grounded, because the MPI in the PG is grounded, and the
PG/OP socket of the RS 485 Repeater is connected internally with bus segment 1.
Grounded operation of the RS 485 Repeater
For grounded operation of the RS 485 Repeater, you must bridge terminals "M" and "PE" on
the top of the RS 485 Repeater.
Ungrounded operation of the RS 485 Repeater
For ungrounded operation of the RS 485 Repeater, do not interconnect "M" and "PE" on the
top of the RS 485 Repeater. In addition, the supply voltage to the RS 485 Repeater must be
ungrounded.
Wiring diagram
In a repeater configuration with ungrounded reference potential (ungrounded operation), any
interference currents and static charges are discharged to the protective conductor by
means of an RC network integrated in the repeater (refer to the figure below).

3(
0
Q) 0വ
'&
9
/ 0 3( 0
$ % $ %
① Ground busbar

Siemens SIMATIC S7-300 Module data Specifications

General

Series	S7-300
Manufacturer	Siemens
Protection Class	IP20
System	SIMATIC S7-300
Digital Inputs	Varies by module
Digital Outputs	Varies by module
Analog Inputs	Varies by module
Analog Outputs	Varies by module
Central Processing Unit	Varies by CPU model
Supply Voltage	24V DC or 120/230V AC
CPU Type	Varies (e.g., CPU 312, CPU 315, etc.)
Memory	Varies by CPU model
Communication Interfaces	MPI, PROFIBUS
Programming Languages	LAD, FBD, STL, SCL, GRAPH
Operating Temperature	0°C to 60°C
Storage Temperature	-40°C to 70°C
Relative Humidity	10% to 95% (non-condensing)