Siemens SIMOVERT MASTERDRIVES Manual page 301

Communication / PROFIBUS
Sequence of a PKW
task
NOTE
8.2-14
The following sequence is necessary for handling a PKW task:
1. With the function DDLM_Write, a PKW task is transferred in the data
block with the index 100 to the CBP.
2. A positive acknowledgement of DDLM_Write is awaited.
3. With the function DDLM_Read, the PKW reply is requested by the
CBP in the data block with the index 100.
4. The PKW reply to the task is contained in the positive
acknowledgement of DDLM_Read.
The contents of the data block with the index 100 corresponds to the
structure of the PKW area of the telegram in accordance with the USS
specification.
With the PKW (parameter identifier value) area, any parameter in the
converter can be visualized and/or altered. The mechanisms of task/reply
IDs necessary for this are described later in the chapter 8.2.3
"Mechanisms of PKW processing".
In the MSAC_C1 channel, larger amounts of data can be transferred at
the same time than by means of PPOs in the cyclical channel. The whole
data unit is used exclusively for transmitting parameters.
It offers the same possibilities, however, as in the USS specification, i.e.
complete arrays can also be processed with one task (IND = 255). All
values of the array are directly transmitted one after the other in a data
block. The maximum length of a data block is 206 bytes.
Function ID Slot No.
1 2 3
PKE IND
1 2 3
Fig. 8.2-6 Structure of PKW data in cyclical data transfer
Process data (PZDs) cannot be stipulated via this acyclical MSAC_C1
channel.
Total telegram
Protocol frame
(trailer)
Read / Write
Index Length
4
PKW data
PWE1 PWE2
4 5 6 7 8
6SE7087-6QX70 (Version AG)
Compendium Motion Control
Protocol frame
Data unit
(trailer)
max. 244
Data unit
5-210 (max. 240)
PWE101
205 206
Siemens AG
SIMOVERT MASTERDRIVES
05.2006