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ON/OFF Control Hysteresis (CHYS)
The controller can be placed in the ON/OFF control mode by setting the
proportional band to 0.0%. The control hysteresis value affects only the
control outputs. Alarms have a separate hysteresis setting. See ON/OFF
Control, page 47, for more details.
CHYS - 1 to 250
The hysteresis band should be set to a minimum value to eliminate output
chatter at the setpoint. Generally, 2 to 5 is sufficient for this purpose. Set the
hysteresis band to factory setting prior to invoking Auto-Tune. After
Auto-Tune, the hysteresis band has no effect on PID Control.
Auto-Tune Code (tcod)
Prior to invoking Auto-Tune, the Auto-Tune code should be set to achieve
the desired dampening level under PID Control. After Auto-Tune is complete,
changes to "tcod" parameter have no effect until Auto-Tune is restarted. When
set to 0, this yields the fastest process response with possible overshoot. A
setting of 2 yields the slowest response with the least amount of overshoot.
Dampening codes of 0 or 1 are recommended for most thermal processes.
Figure 15, Auto-Tune Code
Main Linear DC Output Range (ANtP) (Optional)
Select the type of output range:
0-10 = 0 to 10 V
0-20 = 0 to 20 mA
4-20 = 4 to 20 mA
The linear DC output range jumper must be set to match the range selected.
See Linear DC Output Jumper Selection, page 11. The linear DC output can
be re-calibrated to provide up to 5% of over range operation. See Main or
Second Linear DC Analog Output Calibration, page 69.
Main Linear DC Output Source (ANAS) (Optional)
The output can be programmed to transmit one of the below variables:
OP - Output Power % control
INP - Temperature retransmission
SP - Setpoint (local or remote) retransmission
For Linear DC Output control, the main output (O1) can be disabled by
setting the Cycle Time (CYCt) to 0 in Output Parameter 2-OP or configuring
it as an alarm in Alarm 1 Action (ACt1) in Alarm Parameter 4-AL. For
heat/cool with 4 to 20 mA control applications, the heat (0 to 100%) will be 12
to 20 mA and the cool (-100 to 0%) will be 4 to 12 mA. Notice that 0% (no heat
or cool) is 12 mA.
Main Linear DC Update Time (ANUt) (Optional)
To reduce excess valve actuator, or pen recorder activity, the update time
of the linear output can be set over the range of 0.1 to 250 seconds. A value of
0 seconds results in an update time of 0.1 second.
Main Linear DC Output Scaling Points (ANLO, ANHl) (Optional)
The output is scaled based on the Output Source (ANAS) display by use of
low and high scaling parameters. Reverse acting output is possible by
reversing the scaling points.
ANLO
–
Display value that corresponds to 0 V, 0 mA, or 4 mA as
selected.
ANHI
–
Display value that corresponds to 10 V or 20 mA as
selected.
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Troubleshooting
