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 TM5PCDPS PCI 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).