78 Program features
Tracking
In tracking mode, the PID block output is set directly to the value of parameter 40.50
Set 1 tracking ref selection (or 41.50 Set 2 tracking ref selection).The internal I term
of the PID controller is set so that no transient is allowed to pass on to the output, so
when the tracking mode is left, normal process control operation can be resumed
without a significant bump.
Parameters
Parameters: 96.04 Macro select, groups 40 Process PID set 1 and 41 Process PID
set 2.
Mechanical brake control
A mechanical brake can be used for holding the motor and driven machinery at zero
speed when the drive is stopped, or not powered. The brake control logic observes
the settings of parameter group 44 Mechanical brake control as well as several
external signals, and moves between the states presented in the diagram on
page 79. The tables below the state diagram detail the states and transitions. The
timing diagram on page 81 shows an example of a close-open-close sequence.
Inputs of the brake control logic
The start command of the drive (bit 5 of 06.16 Drive status word 1) is the main control
source of the brake control logic. An optional external open/close signal can be
selected by 44.12 Brake close request. The two signals interact as follows:
• Start command = 1 AND signal selected by 44.12 Brake close request = 0
→
Request brake to open
• Start command = 0 OR signal selected by 44.12 Brake close request = 1
→
Request brake to close
Another external signal – for example, from a higher-level control system – can be
connected via parameter 44.11 Keep brake closed to prevent the brake from opening.
Other signals that affect the state of the control logic are
• brake status acknowledgement (optional, defined by parameter 44.07 Brake
acknowledge selection),
• bit 2 of 06.11 Main status word (indicates whether the drive is ready to follow the
given reference or not),
• bit 6 of 06.16 Drive status word 1 (indicates whether the drive is modulating or
not).
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