Data Model and Tasks

Introduction

The selection of the data model is done at module insertion in your Control Expert project. The data model choice is depending on the platform and localization of the module in the racks.

Topological or Device DDT

The following table compares the two data models:

	Topological	Device DDT
Variable number and creation	One variable per channel to be created with predefined T_CPT_FLM_IN2 type	One variable per module automatically created with T_CPT_FLM_IN2 type
Comply with M340 platform	Yes	No
Comply with M580: In local rack In remote I/O rack	Yes	Yes
Comply with M580: In Ethernet remote I/O rack In Hot Standby configuration	No	Yes
Task assignment	Per channel	Per module(1)
Enables event task	Yes	No
Enables time stamping	Yes	Yes
(1) Both channels of the module are always assigned to the same task.

Task Assignment

The following table gives allowed type of task execution:

PLC	FAST	MAST	AUX0	AUX1
M340	Periodic	Periodic or cyclic	None	None
M580	Periodic	Periodic or cyclic	Cyclic	Cyclic

NOTE: Applications with the BMXETM0200H module preferably require periodic tasks.

The period of the periodic task should be equal or a multiple time of the configured Sampling rate.

Event Task

When using the topological data model (IODDT), the module can trigger the EVT PLC task at each sampling period.

The application can be fully synchronized with the refreshed data provided by the module. To do so, enable the event sources with the variable EVENT_SOURCE_ENABLING, and the module triggers the event task to be executed.

All variables with the EVT prefix are refreshed when the event task starts:

Values on event.
Boolean of the EVT_SOURCES word.