S7-200 Signal modules


The SIMATIC S7-200 Micro PLC provides a full range of communication capabilities.
The integrated RS485 interfaces can be operated at data transmission rates from 1.2 to 187.5 kbaud:

  •  As system bus with up to 126 participants: Programming devices, SIMATIC HMI products and CPUs can be networked without a hitch. In pure S7-200 networks this is accomplished with the integrated PPI protocol. In a network composed of Totally Integrated Automation components, such as SIMATIC S7-300/400 or SIMATIC HMI, the S7-200 CPUs are integrated as MPI slaves.

  •  In the freely programmable mode up to 115.2 kbaud, with user-specific protocols such as ASCII (this supports interconnections with a modem, printer, barcode reader, PC, third-party PLC and any other device). Up to 32 SIEMENS frequency converters can be controlled without additional hardware by using USS protocol instructions.

A connection to a Modbus RTU network can be established via the Modbus protocol instructions.


Modem communications

The S7-200 CPUs can be accessed nearly anywhere in the world by modem via wired network or radio.

  • Teleservice: the modem communication option is useful for avoiding expensive service calls. Two modems are all you need for remote use of the complete range of functions such as program transfer, status or control; the communications tools are integrated as
    a standard feature. External modems can be used as local modems.

  • Telecontrol: you can call up messages and measured values via modem as well as define new setpoints or commands. In this case, one base station S7-200 can control a nearly unlimited number of remote stations. The protocols for data transmission are freely selectable, e.g. for text messages directly to a cell  phone, error messages to a fax machine or Modbus RTU.

Speedy PROFIBUS connection

All CPUs from 222 upwards can be run via the EM 277 communications module as a norm slave on a PROFIBUS DP network with a transmission rate of up to 12 Mbit/s. This open feature of the S7-200 to higher level PROFIBUS DP control levels ensures you can integrate individual machines into your production line. With the EM 277 expansion module, you can implement PROFIBUS capability of individual machines equipped with S7-200.

Powerful AS-Interface connection

The CP 243-2 turns all CPUs from 222 upwards into powerful masters on the AS-Interface network. According to the new AS-Interface specification V 2.1, you can connect up to 62 stations, making even analog sensors easy to integrate. With AS-Interface, you can connect up to 248 DIs + 186 DOs in the maximum configuration. The max. number of 62 stations can include up to 31 analog modules. The configuration of the slaves and reading/writing of data is supported by the handy AS-Interface Wizard.

Design and functions

The built-in RS 485 interfaces can operate at data transmission rates up to 187.5 kbit/s functioning as follows:

  • As a system bus with a maximum of 126 stations. In this capacity, it is possible to network programming devices, SIMATIC HMI products and SIMATIC CPUs without a problem.
    The integrated PPI protocol is used for pure S7-200 networks supporting multiple masters from a single port. In a network consisting of other Siemens components (SIMATIC S7-300/400 and SIMATIC HMI, etc.), the S7-200 CPUs are integrated as MPI slaves.

  • In Freeport mode (up to max. 115.2 kbaud) with user-specific protocols (e.g. ASCII protocol). This means the SIMATIC S7-200 is open for any connected device; for example, it enables connection of a modem, barcode scanner, PC, non-Siemens PLC and much more. By means of the USS protocol for drives, as many as 32 Siemens frequency converters can be controlled without additional hardware.

  • The Modbus RTU Library included in the package also enables connection to a Modbus RTU network as a Master or a Slave.

OPC Driver with PC Access

PC Access is the ideal basis for data exchange between S7-200 and a connected PC – regardless of the communication link selected (PPI, modem, Ethernet/IT CP). As an OPC Server, PC Access offers you the option of writing or reading S7-200 data with Microsoft Excel, or any other OPC client application.

As an OPC Client, it can be used for ProTool Pro, WinCC flexible RT, Win CC, etc. With capability up to 8 connections, the configuration, programming and monitoring can be implemented from a central location, saving both time and money. The Internet Technology module CP 243-1 IT also offers you fast access by permitting a simple universal connection of the PLC to different computers by means of FTP, HTTP, JAVA, and e-mail. The Ethernet module CP 243-1 allows you to access S7-200 process data quickly over Ethernet for archiving or further processing. The configuration support from STEP 7-Micro/WIN ensures simple commissioning and convenient diagnostic options.

Integrated PPI interface

Integrated PPI interface as S7-200system bus or as freely programmableinterface – for connecting printers,barcode scanners, etc.

PROFIBUS DP slave EM 277

From CPU 222 upwards PROFIBUS capable via PROFIBUS DP slave module

AS-Interface master CP 243-2, max. 2 modules

From CPU 222 upwards functionality as AS-Interface master via AS-Interface module

Modem module EM 241

EM 241 modem module with complete functions for PLC communications such as remote maintenance, telecontrol, remote diagnostics, reporting, remote data transmission, etc.

Internet Technology module CP 243-1 IT, max. 1 module

CP 243-IT, Internet Technology module for communication via FTP, e-mail or HTTP


SINAUT MD720-3 GSM/GRPS modem; IP communication via GSM NET; quadband

Ethernet module CP 243-1, max. 1 module