9 PROFIBUS I/O MODULE (PIOMB) FUNCTION BLOCK
9.1 PIOMB block overview
The PIOMB function block represents a physical I/O PROFIBUS device. It provides the user-visible interface
between the control strategies and the process data on a device. The PIOMB also performs the scaling of the
raw process data from the device. The PIOMB is used to encapsulate the data from a PDC of a DSB. Control
data that flows in and out of the C300 Controller passes through the PIOMB to and from the PROFIBUS I/O
channel blocks. Note that process data is not available for the control strategies from the PIOMB directly. It is
made available to the PROFIBUS I/O channel blocks that are assigned to the PIOMB. For more information on
the PROFIBUS I/O channel blocks, see "PROFIBUS I/O channel blocks" on page 213.
In addition to the channel process values, the PIOMB FB also receives and provides the process data status that
reflects the health of the slave device as well as the connection between the PGM and the C300. The PIOMB
does not support any command or configuration parameters for directly controlling a device. The DSB is the
means by which to access device specific data including the diagnostics information.
The PIOMB function blocks are located in the PGM_IF library in the Control Builder. These blocks can be
dragged and dropped into the CEE in the C300. The only configuration required by the user is associating the
PIOMB block with a PDC of a DSB contained within a PGM. Only one PDC can be associated with a given
The number of PIOMB blocks that can be instantiated or loaded to the C300 is limited by the controller
resources including the total amount of process data provided and consumed by the C300, CEE memory, and
Loading a PIOMB FB is identical to loading other function blocks. A PIOMB block can be loaded only when it
is successfully associated with a PDC.
9.1.1 PIOMB block creation
A PIOMB block is created by dragging a PIOMB module template from the Library tab and assigning it to the
CEE of the C300 Controller in the Project view.
You can also create a PIOMB block in the Control Builder from the File menu
(File > New > I/O Modules > PGM_IF > PIOMB - Profibus I/O Module Block).
9.1.2 PIOMB block deletion
You must inactivate a PIOMB before deleting it from the Monitoring view.
A CEEC300 cannot be deleted from the Project view in Control Builder unless all the contained blocks
including the PIOMB and the Control Modules containing the PROFIBUS I/O channels are deleted. After the
contained blocks are deleted, the communication with the PGM ceases.