4.1.3
Parameter value PWE
The data for the PNU-variable is contained in the PWE, and is placed flush right:
4-byte data (double-word)
PWE 5-8 (PWE 8 LSB)
Commands are transferred with task ID 3. If a command cannot be executed, the response identifi-
cation AK = 7 signals the error, and an error number is given out. The error numbers are described
on page 17.
4.2
The process data channel
Cyclical data are exchanged across the PROFIBUS through the process data section of the 20-byte
telegram. Each PROFIBUS cycle triggers an interrupt in the PMCtendo DD4. This has the effect
that new process data are exchanged and processed. The interpretation of these process data
depends on the operating mode that is set. The operating mode is set through a PROFIBUS param-
eter (PNU 930,
ð
p. 23).
In all operating modes, the data word 1 of the process data (PZD1) in the direction from control sys-
tem -> PMCtendo DD4 is used for instrument control, and in the direction from PMCtendo DD4 ->
control system it has the function of a status indicator for the drive.
The interpretation of the process data PZD2 – PZD6 changes, depending on the operating mode,
as can be seen in Chapter 6.2.
Caution:
When the PMCtendo DD4 is switched on, the operating mode that is set is always –126 (safe
state). Before changing the operating mode, bit 10 of the control word STW must always be
set to 0. The new operating mode only becomes active when bit 10 of the control word is set
to 1.
- A.4.016.3/3
Page 18
User manual PROFIBUS DP PMCtendo DD4
4 Profile of PMCtendo DD4
