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Example: Requesting the value of the parameter 123 [dec] that has 32 bit data type.
Request identifer (AK) = 1
PNU = 123dec= 0x7B
Therefore: PKE = 0001 0000 0111 1011 = 0x107B
PKW related values in the Output buffer:
Output Buffer |
|
… |
|
PKE |
0x107B |
IND |
0x0000 |
PWE1 |
0x0000 |
PWE2 |
0x0000 |
… |
The slave (controller) should respond to the PKW telegram with the following telegram in the Input buffer:
Input Buffer |
|
… |
|
PKE |
0xYX7B |
IND |
0xXXXX |
PWE1 |
0xXXXX |
PWE2 |
0xXXXX |
… |
Y = AK. It can be 1, 2 or 7. (See the Table 1)
Interpretation of the received data:
Example 1:
Input Buffer |
|
… |
|
PKE |
0x207B |
IND |
0x0000 |
PWE1 |
0x0A5C |
PWE2 |
0xDD50 |
… |
The Response identifier (AK) = 2 which is “Transfer parameter value (double word)” (see Table 2). That means that the requested parameter value is transferred properly. The Parameter value is 0x0A5CDD50 = 173858128 dec.
Example 2:
Input Buffer |
|
… |
|
PKE |
0x707B |
IND |
0x0000 |
PWE1 |
0x0000 |
PWE2 |
0x0001 |
… |
Response identifier (AK) = 7 which is “Not possible to process request” (see Table 2). That means that the request is not performed. Therefore there is no valid parameter valid in PWE.
Because the response identifier is 7, there is an additional error code in PWE2. The error code 1 means “No access rights“ (see Table 3). In this case, there are no access rights to read the Parameter value.