MB_Close block

Short summary

Name

MB_Close

→POU type

→function

Category

more system blocks, blocks for Modbus, block with internal error diagnostic

Graphical interface

images/download/thumbnails/414780121/MB_Close-version-1-modificationdate-1534494751677-api-v2.png

Available since

  • version 1.51.0 (for logi.CAD 3) and version 3.0.7 of the →runtime system
    images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/warning.svg This block is supported

    for →Raspberry Pi and
    for the platform WindowsX86 (incl. the built-in PLC under Windows).

  • version 1.109.0 (for logi.CAD 3) and version 3.19.0 of the →runtime system
    images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/warning.svg This block is supported

    for Raspberry Pi as well as
    for the platforms WindowsX86 (incl. the built-in PLC under Windows) and LinuxX86.

  • version 2.0.5 (for library System) – graphical interface with in-out variable

Functionality

The block closes a →Modbus connection. Afterwards blocks for Modbus must not be called for the closed Modbus connection.

Inputs, outputs

Identifier

→Data type

Description

In-outs
(VAR_IN_OUT):

MBHandle

DINT

handle of the corresponding Modbus connection

Output:

RC

DINT

return code of the function call:

  • 0: call of the block succeeded

  • -1: The resources necessary to establish the connection (e.g. memory) are not available.

  • -2: The requested function of the Modbus stack could not be executed.

  • -3: The forwarded handle is not valid (anymore).

  • -5: There are no more handles to establish the connection (up to 256 connections can be established at present).

  • -6: An internal problem of the Modbus connection occurred.

  • -7: The LibModbus system service has not been loaded and/or you have no permissions to use Modbus (no enabled feature in the license for the →runtime system ).

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

Internal error diagnostic for block

The block checks the following error cases (if applicable for the block):

  • The resources necessary to establish the connection (e.g. memory) are not available.

  • The requested function of the Modbus stack could not be executed.

  • The forwarded handle is not valid (anymore).

  • The requested amount of data cannot be processed by the Modbus connection.

  • There are no more handles to establish the connection (up to 256 connections can be established at present).

  • An internal problem of the Modbus connection occurred.

  • The LibModbus system service has not been loaded and/or you have no permissions to use Modbus (no enabled feature in the license for the →runtime system).

In such an error case, the output ENO of the block is set to value FALSE (or an equivalent). Moreover, the output RC returns the appropriate code (see the above table under RC).

Example for usage within ST-editor

Best practice in order to get to know the usage of the Modbus blocks: Create a new project based on the project template Moving Light with Modbus Access and study this sample project. This project contains a usage of this block.