VVP10 HART
HART
®
VALVE POSITIONER
INSTALLATION, OPERATION, CONFIGURATION AND MAINTENANCE MANUAL
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27
Local Setpoint
It sets the Setpoint value manually when Loop Current Mode is Disabled.
WARNING
When Loop Current Mode is disabled, Setpoint starts to follow parameter
Local Setpoint
directly, not
considering any other Setpoint configuration.
Setpoint Mode
It can be set to Direct or Reverse, directly affecting the
Setpoint.
Direct:
Setpoint follows the 4-20 mA input directly.
For example, 8 mA input (25% of current range 4-20
mA) will cause a 25% Setpoint.
Reverse:
Setpoint follows the 4-20 mA input in reverse
(SP% = 100% - Curr%).
For example, 8 mA input (25% of current range 4-20
mA) will cause a Setpoint of 100% - 25% = 75%.
Figure 3.8 exemplifies the linear behavior of both
modes, affecting the Setpoint either directly or in
reverse
.
Figure 3.8 – Behaviour of direct and reverse Setpoint modes.
Setpoint Limit
It limits the Setpoint value after Setpoint Mode (see
above). It has independent settings for Upper and
Lower Limits.
For example: SP = 0% (after Setpoint Mode) with SP
Low Limit with 10% will force the Setpoint to 10%. SP
= 100% (after Setpoint Mode) with SP High Limit with
95% will force the Setpoint to 95%.
Figure 3.9 exemplifies (in red) the Setpoint values
that are disregarded by the configuration of Current
Limits.
Figure 3.9 - Example of how Setpoint Limits work.
Setpoint Cutoff
Configures cutting values for Setpoint after applying its limits (see above). It has independent Upper and Lower Cutoffs.
Any input Setpoint value that exceeds cut values will force a new SP = 100% (upper cut) or SP = 0% (lower cut).
For example: SP Low Cutoff = 1%. When SP < 1%
(after Setpoint Limits) will be forced to 0% and will
remain in this value until the new input SP rises to a
value above the Lower Cutoff value plus 0.5% (in this
case, when it is higher than 1.5%). SP High Cutoff =
95%. When SP > 95% (after Setpoint Limits) will be
forced to 100% and will remain in this value until the
new input SP descends to a value below the Upper
Cutoff value less 0.5% (in this case, when it is less
than 94.5%).
Figure 3.10 exemplifies Setpoint behavior according
to Setpoint cutting zones.
Figure 3.10 – Example of how Setpoint Cutoff works.
