Actual Position (POSITION LO/HI)
Position actual values must be spread over two process data words, as the position is generally
transmitted as integer32. This means you have to specify both the
Position Actual Value High and
the
Position Actual Value Low (Fig. 7). Scaling of the actual position
→
Section 3.3.5.
Position actual values can only be used in conjunction with the internal
IPOS positioning control. If
the inverter is not fitted with the
IPOS option and its pertinent functions, this setting will be rejected.
Status Word 1 / Status Word 2
Assigning status word 1 or status word 2 to the process input data allows you to access status data,
fault and reference signals. For a description of status words 1 and 2
→
Section 3.5.
Factory Setting of the
PI1-PI3 Actual Value Description
When the factory setting has been activated, the following process output data are defined for the
MOVITRAC
®
31.. inverter:
PI 1 Actual Value Description:
PI 2 Actual Value Description:
PI 3 Actual Value Description:
STATUS WORD 1
SPEED
NO FUNCTION
3.3.4
Enable Fieldbus Setpoints
Re-parameterizing the process output data, e.g. changing the PO2 setpoint description from speed
setpoint to current setpoint is usually done by means of parameter adjustment. Immediately after
changing the PO2 setpoint description from speed setpoint to current setpoint the speed setpoint
(e.g. 3000 1/min) transmitted by the higher-level control could be wrongly identified as current
setpoint (e.g. 3000 %).
To avoid this, a defined interrupt between the process output data and the inverter setpoint processing
is necessary. This interrupt facility is given by parameter
P570 Enable Fieldbus Setpoints = YES/NO
This parameter tells the inverter whether or not the process output data sent by the higher-level
master are valid for the control and setpoint processing. This parameter can only be set to YES or
NO. Fig. 9 shows the parameter functionality.
M
O
VI
TRAC
®
841
E
Q
RUN
BUS
FAULT
PD1
PD2
PD3
P570: Enable fieldbus setpoints
Fieldbus
CONTROL MODE
Process output data (PO)
00319AEN
Fig. 9: Function of the Enable Fieldbus Setpoints parameter
Inverter Control
with Process Data
3
20
MOVITRAC
®
31.. Fieldbus Unit Profile
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