DCS CPU-366 Bedienungsanleitung PDF herunterladen (Seite 78)

GFK-2334A Chapter 6 PROFIBUS Slave Status and Diagnostics 6-13

DP-V1 Write Response (8)

Write Response Command Block – Basic Example

When a DP-V1 master executes a Write Request to a slave, an indication will appear in

the DP-V1 status register of the PLC. The application program must use this information

in order to formulate the appropriate COMMREQ response to the master’s request. The

response format for this COMMREQ is as follows.

Word Dec (Hex) Definition

1 7 (0007) Length of command block

2 0 (0000) Always zero - no wait mode request.

3 8 (0008) Memory type of COMMREQ status word (%R)

4 9 (0009) COMMREQ status word address minus 1 (%R10)

5 0 (0000) Reserved

6 0 (0000) Reserved

7 8 (0008) Write Response command number

8 8 (0008) Memory type to write response (%R)

9 250 (00FA) Starting Address to write response (response written to

%R251)

10 6+x

(0006+x)

Maximum size of response area

11 0-125

(0000-007D)

Master address (range 0 - 125), read from DP-V1 status

12 0-254

(0000-00FE)

Slot (ranges from 0 to 254)

13 0-254

(0000-00FE)

Index (ranges from 0 to 254)

(Word 7) Command Code: Word 7 specifies the Command code for the COMMREQ to

be executed. Write Response = 8

(Word 8) Local PLC - Memory Type: Words 8—9 specify the location in the PLC where

the response will be written. Values for Word 8 are listed on page 6-4.

(Word 9) Local PLC - Memory Starting Address: Word 9 is a 0-based offset that

determines the starting address in the local PLC to which the response will be written. The

value entered is the offset (0-based) from the beginning of PLC memory for the memory

type and mode specified in Word 8. This offset will be either in bits, bytes, or words

depending on the mode specified (for example, if Word 8=16 and Word 9=2, the starting

address will be %I17). Valid ranges of values depend on the PLC’s memory ranges.

(Word 10) Size of Response: Word 10 specifies the length of the expected indication.

The length is always 6 words at a minimum plus the actual DP-V1 data length x. x ranges

from 1 to 120 words. For example, if the expected length of the DP-V1 indication

COMMREQ is 8 words, word 10 should be 6 + 8 = 14.

(Word 12 and 13) Slot and Index: Slot and Index depend on the application. Slot ranges

from 0 to 254; Index ranges from 0 to 254.

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