Watson-Marlow MM440 - Manual (Page 163)

Issue 10/06 3 Functions
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0 163
The maximum number of PZD words per telegram is, for MICROMASTER, limited
to 8 words (USS-PZD length in MICROMASTER is set using parameter P2012). If
only PKW data are to be transferred in the net data block, then the number of the
PZD can also be 0!
Depending on the data transfer direction, always control word 1 or status word 1
are to be transferred in the PZD1. Depending on the data transfer direction, the
main setpoint or the main actual value is always transferred in PZD 2. Additional
setpoints or actual values are set in the following process data PZD3 to PZDn. For
MICROMASTER, if required, control word 2 or status word 2 should be transferred
in PZD4.
Request telegram, master
⇒ slave
PZD1 PZD2 PZD3 PZD4 . . . . . PZD8
Control word
1
Setpoint 1
Control word
2
Setpoint 2 . . . . . Setpoint 6
Response telegram, slave
⇒ master
PZD1 PZD2 PZD3 PZD4 . . . . . PZD8
Status word 1
Main actual
value 1
Actual value 2
status word
2
Actual value
3
. . . . .
Actual value
7
NOTE
¾
A maximum of 8 PZD words
¾ A minimum of 0 PZD words - i.e. no PZD area in the net data area
¾ On the USS bus, PZD n is always transferred before PZD n+1.
¾ For MICROMASTER, double words cannot be transferred in the PZD section.
¾ Data received from MICROMASTER is always interpreted as 16-bit words. The
appropriate de-normalization is implemented by assigning the appropriate
parameters.
¾ If MICROMASTER sends data to the master via the PZD area, then for physical
quantities, a normalization is made to a 16-bit value (4000 hex notation).
¾ The setpoint can be freely assigned to the actual value; This means for example
that the frequency setpoint is transferred in the request telegram in PZD2 so the
actual frequency value can be signaled back in PZD2 in the response telegram
(this also makes sense from a technological/process perspective); or however,
also another actual value – such as the actual torque value, actual voltage
actual value or actual current value. The setpoint can be freely assigned to the
actual value; for example the frequency setpoint is transferred in the request
telegram in PZD2, which means that the actual frequency value can be signaled
back in the response telegram in PZD2 (this also makes sense from a
technological/process perspective) – or also another actual value – such as
actual torque value, actual voltage value or actual current value.