Siemens SIMATIC S7-300 Module data Reference Manual

Analog Modules
4-9
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
4.3 Analog Value Representation
Introduction
This section describes the analog values for all the measuring ranges and output
ranges which you can use with the analog modules.
Converting Analog Values
The CPU processes the analog values in binary form only.
Analog input modules convert the analog process signal into digital form.
Analog output modules convert the digital output value into an analog signal.
Analog value representation with 16-bit resolution
The digitized analog value is the same for both input and output values having the
same nominal range. The analog values are represented as a fixed-point number
in two’s complement. The resulting assignment is as follows:
Bits 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Value of bits 2
15
2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Sign
The sign of the analog value is always contained in bit number 15:
• “0” ³ )
• “1” ³ *
Resolution less than 16 bits
If the resolution of an analog module has fewer than 16 bits, the analog value is
stored left-justified on the module. The lower-order bit positions not used are
padded with zeros (”0”).

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)