5–11 Viewing the Output Percentage Power
Scroll through the tool programs until you come to HAND CONTROL
, then press the scroll key. The
upper display will now show the process value and the lower display will show the percentage power of output 1 (for
example, ). To view the cooling output, press scroll again. If alarm 2 is configured as a cooling output
(A2SF=COOL), the lower display will now show the percentage power of alarm 2 (for example, ). If alarm 2 is
configured as an alarm, this percentage power reading is invalid and should be ignored.
The range of percentage power is from 0–100%. If the unit is configured for on-off control, only 0 or 100 will be
displayed. For a proportional control, the output percentage power represents the percentage of the duty cycle the
output spends in the ON-state. (e.g., if cycle time CYC=10 seconds, and the output spends 4 seconds on and 6 seconds
off during each duty cycle, the lower display would read )
5–12 Manual Control
Follow the procedures from section 5–11, then press and hold the scroll key for 3.2 seconds and release. The controller
will now enter manual control mode. The upper display will begin to flash and the output percentage can now be
adjusted using the up and down keys. Note that manual control mode is not available if the control is configured for on-
off control (PB=0). If it is attempted, an error message (OPER) will appear in the upper display.
Manual control mode should be used:
• When teaching the process
• If the controller fails
Manual control mode is an open loop control. The process may rise to a dangerous temperature. Special attention
must be paid to the process in order to prevent damage to the system.
5–13 Ramp and Dwell
The controller can be configured to act either as a fixed set point controller or as a single ramp controller on power up.
This function enables the user to set a predetermined ramp rate (RAMP) to allow the process to reach the set point
temperature gradually, producing a “soft start” effect.
A dwell timer is incorporated in the controller. Alarm 1 can be configured to provide either a dwell function or a soak
function when used in conjunction with the ramp function.
Ramp Function
If the ramp function is selected, the process will increase or decrease at a predetermined rate during initial power up, or
with set point changes or process variations.
The ramp rate is determined by the “RAMP” parameter, which can be adjusted through a range from 0–99.99°F/minute
(0–55.55°C/minute). If the “RAMP” parameter is set to zero, the ramp function is disabled.
In the example below, RAMP is set at 5.00°F/minute, the ambient temperature is 50°F, and power is applied at zero
time. The process value climbs to the initial set point of 150°F over a period of 20 minutes. The process temperature is
held until the set point value is changed to 175°F at 40 minutes. The process value then climbs to the new set point over
a period of 5 minutes and the new set point is held. At 70 minutes, the set point value is decreased to 100°F and the
process value falls to the new set point over a period of 15 minutes.
20
20
40
45
Time (minutes)
∞
F
0
175
150 PV
50
100
70
85
