Parker Compax3 Fluid T40

Parker EME
Communication
192-121102 N04 June 2008 357
6.4.4. Acyclic parameter channel
In this chapter you can read about:
Parameter access with DPV0: Required data channel ....................................................357
Data formats of the bus objects........................................................................................363
Compax3 supports parameter access with DPV1.
6.4.4.1 Parameter access with DPV0: Required data channel
You can use the PKW mechanism for acyclic access to parameters in cyclic data
exchange as well. This is made available to make it possible for the master to have
access to the important device parameters without DPV1 functionality.
The master formulates an order in the PKW mechanism. Compax3 processes the
order and formulates the response.
PKW structure:
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
PKE IND PWE
PKW: Parameter identification value
PKE: Parameter identification (1. and 2. octet) (see below)
IND: Subindex* (3. Octet), 4. byte is reserved
PWE: Parameter value (5th to 8th byte resp. 5th to 12th byte with extended PKW)
PKE structure:
Byte 1 Byte 2
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
AK SPM PNU
AK: Order /response identification (value range 0 ... 15)
SPM: Reserved
PNU: Parameter number
*Reference to the subindex
The information for PNU subindex (parameter number) also applies to PROFIdrive
profile Version 3, i.e., that the subindex is counted starting at 0, while for
PROFIdrive profile Version 2 the subindex is counted starting at 1:
DPV1-
Client (V3)
PKW-
Client (V2)
[1..n]
[0..n-1]
Drive
(V3)
[0..n- 1]
-1
The result of this is as follows:
Profibus master based on PROFIdrive profile Version 3
The subindex of the Profibus No. (PNU) specified in the object list is directly valid.
Example: Example: PNU object forward speed control = 400.1 (as specified).
Profibus master based on PROFIdrive profile Version 2
The subindex of the Profibus No. (PNU) specified in the object list must be
incremented by 1.
Example: PNU object forward speed control = 400.2