PKW OUT Data
PKW OUT data request (PROFIBUS DP client to LTMT main unit) is mapped in modules supporting PKW.
To access a register, you must select one of the following function codes:
-
R_REG_16 = 0x25 to read 1 register
-
R_REG_32 = 0x26 to read 2 registers
-
W_REG_16 = 0x2A to write 1 register
-
W_REG_32 = 0x2B to write 2 registers
|
Word 1 |
Word 2 |
Word 3 |
Word 4 |
||
|---|---|---|---|---|---|
|
Register address |
Toggle bit (bit 15) |
Function bits (bits 8 to 14) |
Not used (bits 0 to 7) |
Data to write |
|
|
Register number |
0/1 |
R_REG_16 Code 0x25 |
0x00 |
– |
– |
|
R_REG_32 Code 0x26 |
– |
– |
|||
|
W_REG_16 Code 0x2A |
Data to write in register |
– |
|||
|
W_REG_32 Code 0x2B |
Data to write in register 1 | Data to write in register 2 | |||
Depending on the PLC platform used, refer to the PKW OUT description in little and big endian formats to know the positioning of each field inside each word.
Any changes in the function field will trigger the handling of the request (except if function code is 0x00).
Toggle bit must change at each consecutive request. This mechanism allows the request initiator to detect that a response is ready by polling the toggle bit in response. When this bit in the OUT data becomes equal to the response emitted toggle bit in the IN data, then the response is ready.