Siemens SIMATIC S7-300 Module data Reference Manual

Analog Modules
4-53
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
4.11 Connecting Resistance Thermometers and Resistors
Note
The necessary connecting cables, which result from the potential connection of the
analog input module and the sensors, are not drawn in the figures shown below.
In other words, you must continue to take note of and implement Section 4.8 with
its generally valid information for connecting sensors.
Abbreviations and mnemonics used in the figures below
The abbreviations and mnemonics used in the figures below have the following
meanings:
I
C+
: Constant-current lead (positive)
I
C–
: Constant-current lead (negative)
M
+
: Measuring lead (positive)
M
–
: Measuring lead (negative)
M
ANA
: Reference potential of the analog measuring circuit
M: Ground terminal
L
+
: Terminal for 24 VDC supply voltage
S–: Detector lead (negative)
Connecting Resistance Thermometers and Resistors
The resistance thermometers/resistors are wired in a four-conductor,
three-conductor or two-conductor connection.
With four-conductor and three-conductor connections, the module supplies a
constant current via terminals I
C+
and I
C–
so that the potential drop occurring on
the measuring cables is compensated. It is important that the connected constant
current cables are directly connected to the resistance thermometer/resistor.
Measurements with four-conductor or three-conductor connections supply a more
precise measuring result due to compensation than measurements with a
two-conductor connection.

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)