MANUAL CONTROL
The controller can be transferred between Automatic Control (closed loop;
On/Off or PID control) and Manual Control (open loop; where the control does not work from the setpoint or process feedback.)
Manual operation provides percentage of control of the main output (per the direct or reverse action configured in Output Parameter 2-OP OPAC) from 0 to +100% power. When A2 is configured for cooling (O2), Manual operation still provides 0 to 100% power to the main (O1) output and provides percentage of control to cooling (O2) output from -100% to 0% power.
(Negative percent power is positive cooling (O2) percent power.)
To allow front panel switching between control modes, the Transfer
Parameter (trnF) must be enabled (Enbl) in Lockout Module (3-LC). The user can then select Manual Control from the Hidden Function Mode using
Transfer Parameter (trnF). The percent output power is then adjusted with the
Up and Down arrow buttons in the Normal Display Mode with the %P and
MN annunciators illuminated.
In Time Proportional output control (relay, logic, or triac) the percent output power is converted into output on time using Time Proportioning
Cycle Time (CYCt) value in Output Parameter Module (2-OP). For example with 4 cycle time and 75% power, the output will be on (4 x.75) for 3 seconds and off for 1 second.
In Linear DC output control (0-10 VDC or 0/4-20 mA), the percent output power is converted into a linear value per the Linear output low scaling value
(AnLO) and Linear output high scaling value (AnHI) in Output Parameter
Module (2-OP). For example with 0 VDC (scaled 0.0%) to 10 VDC (scaled
100%) and 75% power, the linear DC output will be 7.5 VDC.
When transferring the controller mode from or to Automatic Control, the controlling outputs remain constant, exercising true “bumpless” transfer.
When transferring from Manual to Automatic, the power initially remains steady but integral actions corrects (if necessary) the closed loop power demand at a rate proportional to the Integral Time. The low (OPLO) and high
(OPHI) output power limits in Output Parameter (2-OP) are ignored when the controller is in Manual Control.
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