Siemens Simatic S7 Series User Manual

13
Analog Inputs and Outputs Analog inputs and outputs are continuous, variable signals.
Typical analog signals vary from 0 to 20 milliamps, 4 to
20 milliamps, or 0 to 10 volts.
In the following example, a level transmitter monitors the level
of liquid in a storage tank and sends an analog signal to a PLC
input. An analog output from the PLC sends an analog signal to
a panel meter calibrated to show the level of liquid in the tank.
Two other analog outputs, not shown here, are connected to
current-to-pneumatic transducers that control air-operated flow-
control valves. This allows the PLC to automatically control the
flow of liquid into and out of the storage tank.
Central
Processing
Unit
(CPU)
Analog
Input
Analog
Output
PLC
0
0.2
0.4
0.6
0.8
1.0
Level
Transmitter
Storage
Tank
Panel
Meter
CPU The central processor unit (CPU) is a microprocessor system
that contains the system memory and is the PLC’s decision-
making unit. The CPU monitors inputs, outputs, and other
variables and makes decisions based on instructions held in its
program memory.
SF/DIAG
I0.0
I0.1
Q0.0
Q0.1
I0.4
I0.5
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Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.