Siemens Simatic S7 Series System Manual

Libraries
9.3 Modbus library instructions
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
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9.3
Modbus library instructions
9.3.1
Modbus communication overview
9.3.1.1
Modbus library features
When you install STEP 7-Micro/WIN SMART, the Siemens Modbus library is also installed.
The Modbus library makes communicating to Modbus RTU master and slave devices easier
by including pre-configured subroutines and interrupt routines that are designed for Modbus
RTU communication.
Modbus communication over RS-485 (integrated port 0 and optional signal board port 1) and
RS-232 (optional signal board port 1 only) is supported for both master and slave devices.
Modbus master instructions can configure the S7-200 SMART to act as a Modbus RTU
master device and communicate to one or more Modbus RTU slave devices.
Modbus slave instructions can configure the S7-200 SMART to act as a Modbus RTU slave
device and communicate with Modbus RTU master devices.
Open the libraries folder in the instruction branch of the project tree for access to the Modbus
instructions. When you place a Modbus instruction in your program, one or more associated
POUs are automatically added to your project.

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.