S7 Programming Tools

S7 is famous in world wide automation industry There are two main programming tools available to S7 control engineers building applications.

STEP 7

Also known as Step 7 Classic, this is the original program development tool provided with the introduction of the SIMATIC S7 programmable controller family. It is still used for program development and troubleshooting of the legacy S7-300 and S7-400 programmable controllers.

TIA PORTAL

The Totally Integrated Automation Portal (TIA Portal) is much more than just a programming tool. It does everything including digitalized automation services, digital planning, and?integrated engineering transparent operation. It is part of the Siemens Digital Enterprise Suite which includes the Product Lifecycle Management (PLM) and Manufacturing Execution System (MES) products.

The TIA Portal can be used for newer S7-300/400 systems and it is a much more user-friendly tool than Classic Step 7.

Communication Options

The S7 family of controllers supports a wide range of communication media (see the table below).?

Note:?Not all communication media options are available on every controller.

MPI

The backplane media communications used by SIMATIC S7-400 for communication between co-processors.

INDUSTRIAL ETHERNET

Standard 802.3 Ethernet communications for supporting OPC UA, S7 communications, Modbus TCP, PROFINET and other protocols.

PROFIBUS

High-speed (12 Mbit/s) RS-485 communications for supporting PROFIBUS DPSERIALStandard serial interface (RS-232/RS-422/RS-485)

SIMATIC S7 controllers support a wide range of communication protocol options that provide controller-to-controller communication, controller-to-operator interface communication, and communication with non-SIMATIC devices (see the table below). Communication is provided by various components on different programmable controllers. Communication can originate with the CPU itself, the Communications Processor (CP), or the Communications Module (CM).?

Note:?Not all communication protocol options are available on every controller.

GLOBAL DATA COMMUNICATION

Small message packet CPU-CPU data exchange for S7-300 and S7-400 controllers over MPI using the S7 Protocol. Global data communication is connectionless using communication blocks GD_SND and GD_RCV.

S7 BASIC

Used for CPU-CPU data exchange with a CPU within the station (expansion unit) or outside the station. Inside the station, MPI is used; outside the station, communication is over PROFIBUS with one station assuming the role of the PROFIBUS end device. Communication blocks I_PUT, I_GET, X_PUT, X_GET, X_SEND and X_RCV are used.

S7 PROTOCOL

The backbone of Siemens communications and supported by the entire SIMATIC product line. Media independent, the S7 protocol is used with MPI, PROFIBUS, and Industrial Ethernet media. S7 protocol is used by SIMATIC CPUs, Control Processors (CP), and Communication Modules (CM). Communication blocks BSEND/BRCV, USEND/URCV, AG_SEND/AG_RECEIVE, and PUT/GET are used.

AG_Send and AG_Receive are some of the most used instructions. GET/PUT are one-way communications mechanisms meaning the other controller is unaware of the communications.

PROFINET CONTROLLER

A high-level Ethernet network for industrial automation applications built on standard Ethernet technologies. It uses traditional Ethernet hardware and software to define a network that structures the task of exchanging data, alarms, and diagnostics with programmable controllers and other automation controllers.

PROFINET controller is the programmable controller side of controller-end device communication.

PROFINET DEVICE

PROFINET Device is the end-device side of controller-end device communication.

PROFINET IRTIsochronous Real-Time (IRT) is a very high-speed communications mechanism used primarily for motion control applications. IRT is implemented using a custom ASIC.

PROFIBUS DP MASTER

Decentralized Periphery (DP) is an industrial automation fieldbus (PROFIBUS media) providing relatively high data speed, low connection costs, and plug-and-play operation.

PROFIBUS DP Master is the programmable controller side of a controller end device communication.

PROFIBUS DP SLAVE

PROFIBUS DP Slave is the end-device side of a controller end-device communication.

OPC UAThe next generation of OPC technology. A more secure, open and reliable mechanism for transferring information between servers and clients than standard OPC.

OPEN COMMUNICATIONOpen Communication represents the series of open, standard Ethernet protocols supported by SIMATIC controllers. Supported open protocols include TCP, ISO (International Standards Organization) on TCP, UDP, and ISO.

Content for this kind of communication is undefined. Both the sender and receiver must agree on the contents of the message.

MODBUSSimple communication protocol developed by Modicon. Uncomplicated data representation and memory addressing, requiring almost no resources. Used over RS-485 media.

MODBUS TCPEthernet version of Modbus with the same data representation and command structure using a TCP transport.

ASCIIData transfer of ASCII characters using configurable end-of-message criteria such as carriage return or dollar sign ($).

There are three operations modes available in S7: Client, Server, and Partner.

1. In?Client?mode, the programmable controller initiates communications and can read and write to another S7 programmable controller, HMI, or other end-device
2. In?Server?mode, the programmable controller waits for another controller or end device to initiate communications
3. In?Partner?mode, each end of the communications link can exchange unsolicited data once the connection is established