Consequently, the speed setpoint processing of the MOVITRAC
®
31.. inverter is subject to the
priorities shown in the table.
Processing priority in the inverter
Setpoint source
Highest priority:
Internal fixed setpoints
Motorized potentiometer
Fieldbus setpoint
Lowest priority:
Analog setpoint (unipolar)
If the speed setpoint is not specified via the bus system, the analogue input will become the setpoint
source, even though the control mode is set to “Fieldbus”. This option permits applications to be
implemented where the control signals (enable, controller inhibit etc.) are specified via the fieldbus,
while the setpoint is specified by an automation unit, which does not have a fieldbus interface.
Relative Speed Setpoint (speed [%])
With the parameter speed [%] set the inverter MOVITRAC
®
31.. interprets the setpoint transmitted
in this process data word as percental speed setpoint. The scaling of the speed setpoint is described
in section 3.3.5.
With the assignment of the relative speed setpoint to a process output data word the analog setpoint
is deactivated automatically. The execution of internal setpoint functions such as the selection of
internal fixed setpoints or motor potentiometer is higher-level, this means that in these cases the
speed setpoint set via fieldbus is not effective!
With the setpoint descriptions SPEED and SPEED [%] a speed setpoint is specified generally.
Consequently programming both setpoint variants at the same time is technically not efficient and is
treated as double assignment of the process-output data channel, which means that only the first
speed setpoint programmed is processed by the inverter.
The relative speed setpoint always refers to the current applicable maximum limit of the speed or
frequency f
max
, this means a percental setpoint of 100% is generally equivalent to the current
applicable value of f
max
, whereas a set value of 0% is generally equivalent to 0 Hz. Due to the fact that
f
max
is the active maximum limit, setpoints higher than 100% cannot become effective. In the case of
a setpoint entry higher than 100% the frequency f
max
is set.
Position-Setpoint (POSITION LO/HI) (not for MOVITRAC
®
31.., size 0)
Position setpoints may only be used in conjunction with the internal
IPOS positioning control. Unless
the inverter is fitted with the
IPOS option and its pertinent functions, this setting will be rejected.
Position setpoints must be spread over two process data words, as the position is generally entered
as a signed 32-bit value (integer32). You must therefore specify the more significant position setpoint
(
POSITION HI) and the less significant position setpoint (POSITION LO) (Fig. 7). Otherwise the
inverter will not respond to the position entry. Scaling of the position setpoint see Section 3.3.5.
Inverter Control
with Process Data
3
14
MOVITRAC
®
31.. Fieldbus Unit Profile
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
