GRUPO DE ESTUDIOS SOBRE CIUDAD Y TERRITORIO

Overview ISO transport provides services for transmitting data via links. The link is automatically monitored by the ISO transport service.

The ISO transport service (ISO 8073 Class 4) corresponds to Level 4 of the ISO reference model.

Features Large quantities of data can be transmitted using the ISO transport service due to "data blocking", i.e. useful data can be segmented in several data telegrams.

The ISO transport service facilitates communication to any communica- tion partner (e.g. SIMATIC S5 or PC) that supports sending and receiving data in accordance with ISO transport.

Data is only transferred on Industrial Ethernet with the ISO transport serv- ice.

Transmission Reliability

A high degree of data security is achieved due to automatic repetition in the case of ISO transport and additional block checking mechanisms (CRC check on Layer 2).

Receipt of data is acknowledged by the ISO transport service of the com- munication partner. This is indicated in the appropriate block.

Integration in STEP 7

With the ISO transport services, the SIMATIC S7 family offers communi- cation functions for sending and receiving data via static links. The asso- ciated ISO transport links are configured using STEP 7. They are estab- lished when the station starts up.

The STEP 7 "NCM S7 for Industrial Ethernet" option package supple- ments the STEP 7 link configuration with the "ISO transport" link type.

Assignment to Software Interface

In SIMATIC S7, the ISO transport services are used for communication with the blocks AG_SEND and AG_RECV via the Industrial Ethernet sub- net (see Chapter 4).

On the PC, the ISO transport services are provided in the form of C func- tions.

Communication Services

Communication with SIMATIC

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2.4 ISO-on-TCP Services

Overview The ISO-on-TCP service corresponds to the standard TCP/IP

(Transmission Control Protocol/Internet Protocol) with the extended RFC 1006 in accordance with Layer 4 of the ISO reference model.

RFC 1006 is required because TCP provides data stream communication without blocking the data into messages.

This behavior is rectified in the case of the ISO protocol of Layer 4 with an end of message code (EOM). The EOM allows messages (data blocks) to be transmitted. TCP/IP does not recognize this. Additive protocols have to used for the purposes of sending messages. RFC 1006 describes how the services of ISO layer 4 can be mapped onto TCP. RFC 1006 is an official standard and is used by many manufacturers.

Features The ISO-on-TCP service facilitates communication to any communication

partner (e.g. PC or non-Siemens system) that supports sending and re- ceiving data in accordance with ISO-on-TCP.

With the ISO-on-TCP service, data is only transferred on Industrial Ether- net.

Transmission Reliability

A high degree of data security is achieved due to automatic repetition and additional block checking mechanisms (CRC check on Layer 2).

Receipt of data is acknowledged by the communication partner. This is indicated in the appropriate block.

Integration in STEP 7

With the ISO-on-TCP services, the SIMATIC S7 offers communication functions for sending and receiving data via static links. The associated ISO-on-TCP links are configured using STEP 7. They are established im- plicitly when the station starts up.

The STEP 7 "NCM S7 for Industrial Ethernet" option package supple- ments the STEP 7 link configuration with the "ISO-on-TCP" link type.

Assignment to Software Interface

In SIMATIC S7, the ISO-on-TCP services are used for communication with the blocks AG_SEND and AG_RECV via the Industrial Ethernet sub- net (see Chapter 4).

On the PC, the ISO-on-TCP services are provided in the form of C func- tions.

Communication Services

2.5 PROFIBUS-FDL Services

Overview FDL (fieldbus data link) offers services for the transmission of data on the PROFIBUS subnet.

The FDL service of SIMATIC S7 supports the SDA function (send data with acknowledgement).

The FDL service can be placed in Layer 2 of the ISO reference model. PROFIBUS-FDL complies with the European standard EN 50 170 Vol. 2 PROFIBUS.

Features Receipt of data is acknowledged by the FDL service of the communication partner.

The FDL service facilitates communication to any communication partner (e.g. SIMATIC S5 or PC) that supports sending and receiving data in ac- cordance with the SDA function.

Transmission Reliability

A high degree of data security is achieved due to automatic repetition and additional checking mechanisms (parity bit per character and check sum on Layer 2).

Integration in STEP 7

With the FDL service, the SIMATIC S7 offers, communication functions for sending and receiving data via static links. The associated FDL links are configured using STEP 7. They are established implicitly when the PROFIBUS-CP for SIMATIC S7 starts up.

The STEP 7 "NCM S7 for PROFIBUS" option package supplements the STEP 7 link configuration with the link type "FDL link".

Assignment to Software Interface

In SIMATIC S7, the FDL services are used for communication with the blocks AG_SEND and AG_RECV via the PROFIBUS subnet (see Chapter 4).

Communication Services

Communication with SIMATIC

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2.6 PROFIBUS-FMS Services

Overview PROFIBUS-FMS (fieldbus message specification) offers services for the

transmission of structured data (FMS variables).

The FMS service can be placed in Layer 7 of the ISO reference model. It complies with the European standard EN 50170 Vol. 2 PROFIBUS and therefore facilitates open communication with field devices.

Features Services for reading and writing FMS variables via FMS links are avail- able.

Receipt of data is confirmed by the partner with an application acknow- ledgement, i.e. the application running on the distant communication partner has received the data correctly.

Data is only transferred with the FMS service on the PROFIBUS subnet.

Transmission Reliability

A high degree of data security is achieved due to automatic repetition and additional checking mechanisms (parity bit per character and check sum on Layer 2).

Integration in STEP 7

With the FMS service, the SIMATIC S7 offers communication functions for sending and receiving data via static links. The associated FMS links are configured using STEP 7. They are established implicitly when the station for SIMATIC S7 starts up.

The STEP 7 "NCM S7 for PROFIBUS" option package supplements the STEP 7 link configuration with the link type "FMS link".

Assignment to Software Interface

In SIMATIC S7, the FMS services are used for communication with the communication FBs for FMS via the PROFIBUS subnet (see Chapter 4). On the PC, the FMS services are provided in the form of C functions.

Communication Services

2.7 PROFIBUS-DP Services

Overview PROFIBUS-DP services facilitate direct communication with distributed

I/O. From the control program, distributed I/O is addressed as if it were central I/O.

PROFIBUS-DP services comply with the European standard EN 50170 Vol. 2, PROFIBUS. Any standard slave can be connected.

Features The "distributed I/O" expands the central I/O with I/O modules that are connected to a central controller via a parallel bus (via an IM) or a serial bus (interface on CPU, IM or CP). The serial bus is PROFIBUS-DP which covers open communication up to Layer 7.

The PROFIBUS-DP interface is either integrated on the S7/M7 CPUs or separate interfaces are used (IMs, CPs).

The I/O that is located, for example, in an expansion unit (ET 200 station) connected to PROFIBUS as a DP slave, is addressed in the same manner as any other I/O in the central controller or in an expansion unit. This means that the I/O modules can be directly addressed using instructions or they are accessed via process image transfer.

Transmission Reliability

A high degree of data security is achieved due to automatic repetition and additional checking mechanisms (parity bit per character and check sum on Layer 2).

Integration in STEP 7

Distributed I/O is configured using the hardware configuration functions of STEP 7.

This also applies to the system integration of the ET 200 stations.

Non-Siemens slaves can also be integrated into the hardware configura- tion system.

Communication Services

Communication with SIMATIC

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