Acyclic Exchange with PROFIBUS DPV1 Functions

Introduction

The PROFIBUS DPV1 enhancement additionally supports acyclic data exchange between a PROFIBUS DPV1 master and DPV1 slaves. It allows access to %MW variables.

To use these functions between a PROFIBUS DPV1 master and the TM4PDPS1 module, the parameter DPV1Enable must be set to TRUE (default value).

Data Addressing

Data addressing in the logic controller is %MW.

The Profibus status of the controller must be in Operate state; therefore it can be updated even if the logic controller is not running.

The %MW variables are automatically updated by the I/O driver whenever a DPV1 message is received.

It is based on PROFIBUS DPV1 read and write functions.

The logic address is the number of the %MW addressed.

Addressing

2 different types of addressing are available for acyclic exchange:

Addressing Type	Number of Requests for Read/Write %MW Variables	Description
Direct addressing	1	The address of the %MW variable is coded directly by Slot and Index fields. See restrictions in the note below.
Indirect addressing	2	oThe first request sends the address of the first %MW that the master will read or write. oThe second request reads or writes one or several values of the %MW variable.

Addressing Type

Number of Requests for Read/Write %MW Variables

Description

Direct addressing

The address of the %MW variable is coded directly by Slot and Index fields. See restrictions in the note below.

Indirect addressing

oThe first request sends the address of the first %MW that the master will read or write.

oThe second request reads or writes one or several values of the %MW variable.

NOTE:

The following restrictions apply to direct addressing:

oSlot field (DU1): value 0xFF is not allowed

oIndex field (DU2): values 0xFF, 0xE9, and 0xEA are not allowed

The table shows how to create requests for accessing the %MW from the PROFIBUS DPV1 master:

Addressing		DU0: DPV1 Function Number	DU1: Slot	DU2: Index	DU3: Length (in Bytes)	DPV1 Data Frame
Addressing		1 Byte	1 Byte	1 Byte	1 Byte	N Byte
Direct addressing	Write	5F hex (write)	MSB of the %MW address	LSB of the %MW address	Length to read	Values to write
Direct addressing	Read	5E hex (read)	MSB of the %MW address	LSB of the %MW address	Length to write	–
Indirect addressing	Send address (Step 1)	5F hex (write)	1	E9 hex	2	%MW address
	Read (Step 2)	5E hex (read)	1	EA hex	Length to read	–
	Write (Step 2)	5F hex (write)	1	EA hex	Length to write	Values to write

NOTE: The Length field has to have an even value (the length in byte of one %MW is 2).