Watson-Marlow MM440 - Manual (Page 162)

3 Functions Issue 10/06
MICROMASTER 440 Operating Instructions
162 6SE6400-5AW00-0BP0
Parameter value (PWE)
The parameter value (PWE) is transferred, depending on the parameterization of
the word length (refer to parameter "USS-PKW length" P2013) of the PKW area as
word or double word (32 bit). Only one parameter value can be transferred in a
telegram.
If the word length of the PKW area is parameterized with 3 words (P2013 = 3), then
only 16-bit parameters can be transferred. Parameter descriptive elements, that
are greater than 16 bit cannot be transferred.
If the word length of the PKW area is parameterized to be 4 words (P2013 = 4),
then 16 and 32-bit parameters can be transferred. Parameter descriptive elements
that exceed 32 bits cannot be transferred.
If the word length of the PKW area is parameterized with "variable length" (P2013
= 127), then 16, 32-bit parameter and parameter descriptive elements can be
transferred. Further, all elements of an indexed parameter can be read or changed
with a single request, as well as the complete parameter description requested if
the index corresponds to the value 255 (index = 255).
Transferring one 16-bit parameter value:
1. Fixed PKW area, 3 words:
The value is in PWE1
2. Fixed PKW area, 4 words:
The value is in PWE2 (least significant word, 4th word); PWE1 is set to 0.
3. Variable PKW area:
The value is in PWE1. PWE2 and higher not available!
Transferring one 32-bit parameter value:
1. Fixed PKW area, 3 words:
Request is rejected with fault message 103.
2. Fixed PKW area, 4 words:
PWE1 (most significant word; 3rd word) contains the high word of the double
word,
PWE2 (least significant word; 4th word) contains the low word of the double
word.
3. Variable PKW area:
As for 2.; PWE3 and higher not available!
Process data area (PZD)
Process data is continually exchanged between the master and slaves in this area.
At the start of communications it is configured as to which process data is to be
exchanged with a slave. For instance, for slave x, the current setpoint is to be
transferred in the second PZD (= PZD2). This setting remains for the complete
data transfer.
1 word 1 word 1 word 1 word 1 word
PZD1 PZD2 PZD3 PZD4 . . . . . PZD8
PZD1 – PZD8
= process data
= control / status word(s) and setpoint / actual value(s));
The control / status word(s), setpoints and actual values required for the
automation are transferred in this area.
The length of the PZD area is defined by the number of PZD elements (P2012).
Contrary to the PKW area, that can be variable, the length of this area between the
communication partners (master and slave) must always be permanently declared.