Siemens SINAMICS G120 Instructions d'exploitation télécharger pdf (Page 117)

Configuring the fieldbus

6.1 Communication via PROFIBUS

Inverter with CU240B-2 and CU240E-2 Control Units

Operating Instructions, 01/2011, FW 4.4, A5E02299792B AB

115

Example of read request for parameter P7841[2]

To obtain the value of the indexed parameter P7841, you must fill the telegram of the

parameter channel with the following data:

● Request parameter value (field): Bits 15 … 12 in the PKE word:

Request identifier = 6

● Parameter number without offset: Bits 10 … 0 in the PKE word:

Because you can only code parameter numbers from 1 … 1999 in the PKE, you must

deduct as large an offset as possible, a number divisible by 2000, from the parameter

number, and transfer the result of this calculation to the PKE word.

In our example, this means: 7841 - 6000 = 1841

● Coding the offset of the parameter number in the page index byte of the IND word:

In this example: When offset = 6000, this corresponds to a page index value of 0x90.

● Index of parameter in the subindex byte of the IND word:

In this example: Index = 2

● Because you want to read the parameter value, words 3 and 4 in the parameter channel

for requesting the parameter value are irrelevant. They should be assigned a value of 0,

for example.

Table 6- 14 Request to read parameter P7841[2]

PKE (1st word) IND (2nd word) PWE (3rd and 4th words)

AK PNU (10 bits) Subindex

(H byte)

Page index

(L byte)

PWE1

(H word)

PWE2

(L word)

0x6 0 0x731 (decimal: 1841) 0x02 0x90 0x0000 0x0000

Rules for editing requests and responses

● You can only request one parameter per transmitted telegram

● Each received telegram contains only one response

● The request must be repeated until the right response is received

● The response is assigned to a request by means of the following identifiers:

– Suitable response identifier

– Suitable parameter number

– Suitable parameter index IND, if required

– Suitable parameter value PWE, if necessary

● The complete request must be sent in a telegram. Request telegrams cannot be

subdivided. The same applies to responses.

1 2 ... 112 113 114 115 116 117 118 119 120 121 122 ... 303 304

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Siemens SINAMICS G120 Instructions d'exploitation Page 117

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