Monday, September 3, 2012

Wireless Data Communication via GPRS with S7-1200 and CP 1242-7, Scenario 2, Cross communication


The task in general termsThis application refers to the topic of wireless communication between distributed automation stations via GPRS (M2M communication), with and without a control center. The document is broken down into several variants which differ with regard to the transmission protocols and the different hardware components used in the remote stations. It is aimed at providing a selection aid, so as to find the best variant based on the technical parameters and with consideration to the conceptual requirements. Furthermore, this application description focuses on the provision of helpful advise for the configuration and parameter assignment of the selected variant. The task in concrete terms
Each variant is explained in greater detail on the basis of a specific application example. 

  •  Variant 1:
    The filling level of an elevated water tank shall be transmitted to a pump station. For the purpose of remote control and remote visualization, the two distributed stations are already linked to a control center.
  • Variant 2:
    The power supplier and operator of a wind farm shall be able to adjust the output of his wind farm to the current consumption situation in the electricity grid. This shall be effected by means of an I/O connection between several wind turbines and a switching station. There is no control center involved in this system.
  •  Variant 3:
    Several oil production fields are equipped with a series of controllers. They are used for simple automation tasks like the control of pumps, for example. Now, the filling level information from all oil production fields shall be transmitted to a higher-level controller with higher performance capacity, so as to enable global releases for oil production. There is no control center involved in this system.

The variants discussed in this application example (configuration example CE-X21, scenario 2) show, how the given tasks can be solved with the help of SIMATIC components. The central component in this solution is the GPRS modem SIMATIC CP 1242-7. With the help of CPs for the SIMATIC S7-1200 controllers, telegrams can be sent to other CPs or to other IP-capable network participants over a GPRS connection.
A SIMATIC CP 1242-7 GPRS (2) is connected to a SIMATIC S7-1200 controller 1211C (3) via the bus interface. The GSM/GPRS modem is equipped with a SIM card (5) and connection to the air interface is realized with a quad band GSM/GPRS antenna type ANT 794-4MR (4). All components are supplied with power by a SIMATIC PM 1207 power module (1). 

Depending on the specific variant, a further SIMATIC S7-1200 controller in combination with a SIMATIC CP 1242-7, or a SIMATIC S7-300 controller with UMTS/GPRS modem SCALANCE M 873-0 are used.
A UMTS/GSM modem SCALANCE M873-0 (2) is connected to a SIMATIC S7-300 controller 315-2 PN/DP (4). The UMTS/GSM modem is equipped with a SIM card (5) and connection to the air interface is realized with a quad band antenna type ANT 794-4MR (1). All components are supplied with power by a SIMATIC PS307 power module (3). The S7-300 controller is provided with a SIMATIC micro memory card.


For more information,please visit SIEMENS website

Firmware V1.3 for CP 1242-7 GPRS Communication Module for S7-1200 Released for Delivery 



The firmware version 1.3 for the GPRS communication module CP 1242-7 (order number 6GK7242-7KX30-0XE0) has been released for delivery.
The new firmware version contains the following enhancements: 

Connection monitoring of GPRS direct connections
In the case of direct communication between stations in the GPRS Direct Mode, both the passive and the active station will now detect a connection failure on the radio network line. This enables a faster response to the connection failure by the program.
The connection failure is detected by means of a connection watchdog time. The connection watchdog time can be configured in STEP7 under:
    - Device configuration -> CP1242-7 -> Telecontrol Interface -> Keep-alive-Waiting time -> Connection watchdog time (the value 0 means disabling the connection monitoring,
       until now this parameter had no meaning in the GPRS Direct Mode)

Please note: The use of connection monitoring will result in increased data volume, because the stations must exchange cyclic Keep Alive messages. 

Support of new SIM card technologies
All currently available SIM cards can now be employed. A changeover of the SIM card technology of some providers caused isolated problems with the identification of the SIM card. 

Missing SIM card has no influence on the S7-1200 CPU
Even if no SIM card is inserted, the CPU program of the S7-1200 PLC will start up normally. S7-1200-based stations can thus be equipped with the CP1242-7 even if the GPRS functionality is not used from the beginning. 

Enhanced SMS diagnostic option:
Authorized mobile telephone units can enquire extended station information via a text message (SMS) with the text "CPDIAG".

In addition, small bug fixes have been introduced to further improve system stability.

New orders will be shipped with firmware 1.3 from end of August 2012 onwards.

The configuration with Step7 is carried out with the same configuration screen form as for the predecessor version 1.0. A differentiation is neither necessary nor possible.

The current firmware version can be enquired in the Step7 Device Manager via the module status (online connection required). 

 Internet document
 A S7-1200 PLC can be connected to a GSM/GPRS mobile phone network with the new CP 1242-7 communication processor. 

The CP 1242-7 uses the globally available GSM mobile phone network to transmit productive data and diagnostic information of the S7-1200 based on the GPRS data service to other mobile subscribers or to control centers via the Internet.

By using the CP 1242-7, you can use the S7-1200 as Remote Terminal Unit (RTU) in telecontrol and remote maintenance applications. Together with the "TeleControl Server Basic" software (ID: 45500914) you are creating the "TeleControl Basic" telecontrol system with perfectly matched components.

1. Product description

The CP 1242-7 communication processor is used for connection of a SIMATIC S7-1200 to the GSM/GPRS mobile phone network and is characterized by the following features.
·                      provides global wireless data exchange between S7-1200 controllers and/or control centers with Internet connection
·                      communication based on the GPRS (General Packet Radio Service) mobile phone service with data transmission
                      speeds of up to 86 kbps in the downlink and 43 kbps in the uplink
·                      GPRS operation with fixed IP addresses with M2M contract as well as dynamic IP addresses with standard
                      mobile phone contract
·                      Time synchronization based on NTP (Network Time Protocol)
·                      Wake-up functionality by call or SMS to activate CP from "standby mode"
·                      Sending and receiving text messages (SMS)
·                      Clear LED signaling for fast and easy diagnostics
·                      Compact industrial housing in S7-1200 design for installation on standard mounting rail
·                      Fast commissioning due to simple configuration with Step 7
Together with the "Telecontrol Server Basic" software available for telecontrol applications, the CP 1242-7 forms a perfectly matched telecontrol system with additional features:
·                      Connection of up 5,000 telecontrol stations to the control center via OPC interface
·                      Data backup in substations in case of connection failures
·                      Central status monitoring of substations
·                      No special provider services required for fixed IP addresses
·                      Teleservice access to substations with Step 7 via Internet 

2. Area of application
Areas of application for the CP 1242-7 are typically applications with the following properties:
·                      Widely distributed automation solutions must exchange data or be monitored centrally
·                      Mobile machines/vehicles without permanent location need a permanent or temporary communication link
·                      IT safety requirements prevent direct network access of service providers to machines at the end customer's site
·                      Link for difficult to access outposts without network infrastructure

These applications can be found in a variety of industries:
·                      Water/waste water systems - Pump/valve controls
·                      Traffic technology - Traffic light controllers, illumination controls
·                      Power engineering - Monitoring of transformer stations, meter reading
·                      Mechanical engineering - central remote maintenance of machines operated worldwide
·                      Wind energy - Condition monitoring of wind turbines
·                      Vending machine manufacturers - Monitoring, control of beverage vending machines
3. Other
Additional information is available in the Mall and on the Service and Support pages  
Mobile phone products are subject to import regulations. Specific radio licenses are required for most countries.
A list of currently existing country-specific approvals for SIMATIC NET mobile radio products is available here.  
An application example with sample program (Configuration Example) for use of the CP 1242-7 is available on the Support Pages.

Necessary requirements for using the modules:
o                     SIMATIC S7-1200 as of firmware version 2.0
o                     Engineering System Step7 as of version V11 SP1 + Hardware Support Package (HSP CP 1242-7 1.0)
The Hardware Support Package is available on the enclosed product CD and for download on the Support Pages.
Keep in mind that you need Step7 V11 with Service Pack 1 for installation of the Hardware Support Packages. The download of Service Pack 1 is also available on the respective Support Pages

for more information, please visit SIEMENS website

3-Point Stepper Control with SIMATIC S7-1200
The valve of a mixer tap shall be controlled according to a desired given temperature.
A three-way mixing valve with valve actuator is used. The valve is digital controlled in both directions. This is referred to as a 3-point stepper control.
Varying the valve position can yield any mixing ratio of hot and cold entering water and so the water outlet temperature.

For SIMATIC S7-1200 as of firmware V2.0, the development environment STEP 7 V11 provides the "PID_3Step" 3-point stepper control block.

The application on hand provides quick configuration and commissioning of your mixer tap.
The application also contains a simulation of the controlled system, which enables familiarizing yourself with all functions of "PID_3Step".
features can be conveniently operated via KTP1000 Basic PN:
  • Switching between automatic and manual mode
  • Transition time measurement of the valve
  • Visualization of the valve position
  • Trend curves of setpoint, process value and output value
  • Switching between the real controlled system and the simulation
  • Disturbance value control in simulation mode
  • Specifying the behavior in the case of errors and their simulation
  • Specifying the deadband width for energy saving operation
  • Manually specified control parameter and automatic tuning
  • Online monitoring of the "PID_3Step" controller block
  • Modifying the configuration during runtime

For more information,please visit SIEMENS website