Configuring DP mode (S7-300, S7-400, PC) - STEP 7

Reference

Depending on the module type, you configure the PROFIBUS mode in the following parameter group:

• S7-300/400 CPs, PC-CPs: Parameter group "Operating mode" (or "Properties > General > Operating mode".

• S7-1200/1500 CPs: Parameter group "PROFIBUS interface / DP interface > Operating mode"

• LINK modules: Parameter group "DP/MPI interface > Operating mode"

Relationship between CP mode and function of the module

The configurable DP modes and the functions made possible by them can be found in this table:

Key: "X" = Function supported; "-" = Function not supported

"Delay time"

For some modules in DP Master mode, you can set an additional delay for updating the DP I/O data. This delay time is used by the module to process other protocols such as FDL.

DP master class 2 (only some PC-CPs and IE/PB LINK HA)

In this operating mode, the module can read input and output data from any DP slaves that are not assigned to it.

This means, for example, that a process signal can be acquired by several DP masters and can help to save sensors in the field (shared input / shared output). Programming, diagnostic or management devices typically operate as DP class 2 masters.

IE/PB LINK HA

You can assign the "DP master class 2" mode to the LINK.

When this option is enabled, you can use the functions "Read data record" and "Write data record" for DP slaves of another DP master in the user program as well as access the cyclic input data of the external slaves.

The output data sent in the user program of the IE/PB LINK HA controller are discarded by the LINK in this operating mode.

• "DP master class 2"

  You can enable the option under the following conditions:

  • As with the external DP master system, the DP slaves of the external DP master system are additionally configured identically on the LINK, if necessary also via a GSD file. The external slaves are configured as if they were operated directly on the LINK as DP master.

    If the external DP master is a SIEMENS DP master, it must be configured on another PROFIBUS master system.

  • The PROFIBUS profile must be changed to "User-defined". You must enter exactly the bus parameters that the external DP master has calculated for its master system (taking into account an additional active station).

  CiR is not allowed in the "DP master class 2" mode. The LINK cannot be reloaded as "DP master class 2" in RUN mode.

• "Enable reading of the input data from DP slaves"

  You can optionally enable the reading of the input data of the external DP slaves.

  • Option disabled (default)

    If you do not need reading, disabling the option increases the communication speed.

  • Option enabled

    When enabled, the LINK can access the cyclic input data of the external DP slaves.

DP slave mode: Option "Test, Commissioning, Routing"

The name of the function varies depending on the CP type.

• Option enabled: DP slave active

  Select the check box if, for example, you want to use PG functions regularly over this interface for commissioning and testing. This selects the "DP slave active" mode. The interface is then involved in the token circulation of the PROFIBUS.

  The following functions are then possible (the name of the function can vary depending on the CP type):

  • Programming (for example loading)

  • Testing (status/modify)

  • S7 routing (I slave as gateway)

  • S5-compatible communication (SEND/RECEIVE interface)

  • S7 communication (only in server mode on connections configured at one end without communication blocks, configuration on partner)

  Note the following effects of "DP slave active" mode:

  • S7 connections for data exchange using communication blocks cannot be configured in this mode

  • This can extend the token rotation time.

    In time-critical applications and when S7 routing and client functionality are not required for communication, this option should therefore not be enabled.

• Option disabled: DP slave passive

  If the "Test, commissioning, routing" box is not checked, the "DP slave passive" CP mode is selected and the interface only operates as a server for communication services and is not involved in the token rotation on PROFIBUS.

  Server functionality means that only the partner (for example PG, OP or automation system) can initiate communication. Note the following features when the option is not enabled:

  • S7 routing is not possible.

  • Programming and testing are possible but slow (no extension of the bus token rotation time).