Operator Menus; Control Action; Reverse-Acting Control; Direct-Acting Control - ABB AWT420 Operating Instruction

AW T4 2 0 | U N I V E R S A L 4 - W I R E , D U A L- I N P U T T R A N S M I T T E R | O I/A W T4 2 0 - E N R E V. B

Operator menus

The following menu options available from the Operator page/
Start menu enable selection of the Control Mode and
adjustment of Setpoints or Output:
Operator menus
Operator menu
access key
Autoscroll
Manual Hold
In Configuration
Enter Configuration
Control Mode
Control Mode
Auto
Adjust Manual
Operator Views
Data Logs
Logs
Manual Hold
Autoscroll
Enter Configuration
Setpoint/Output adjustment –
direct or reverse-acting controller (1 setpoint)
Control Mode
SPA
Adjust
Output
Operator Views
Data Logs
Logs
Manual Hold
Autoscroll
Enter Configuration
Setpoint/Output adjustment –
dual-acting controller 92 setpoints)
SPA
Control Mode
SPB
Adjust
Output
Operator Views
Data Logs
Logs
Manual Hold
Autoscroll
Enter Configuration
Figure 37 PID control: Control Mode/Setpoint/Output menus
CAL
Use the / keys to
toggle/select Auto or
Manual mode.
Use the / keys to
toggle/select SPA* or
Output mode.
Output mode enabled only
if Control Mode/Manual is
selected.
*SPA = acid setpoint
Use the / keys to
toggle/select SPA*, SPB** or
Output mode.
Output mode enabled only
if Control Mode/Manual is
selected.
*SPA = acid setpoint
**SPB = base setpoint

Control action

Reverse-acting control

• Single control output
• P, P+I, P+I+D or P+D
• Output increases as Process Value deviates below Setpoint
• Output is zero if Process Value is greater than Setpoint*
• Proportional band is positioned below Setpoint
only if Control Mode/Manual is selected – see Figure 37.
*Enabled
Output
100 %
0 %
Proportional
Setpoint
Figure 38 Reverse-acting control

Direct-acting control

• Single control output
• P, P+I, P+I+D or P+D
• Output increases as Process Value deviates above Setpoint
• Output is zero if Process Value is less than Setpoint*
• Proportional band is positioned above Setpoint
only if Control Mode/Manual is selected – see Figure 37.
*Enabled
Output
100 %
0 %
Proportional
band
Setpoint
Figure 39 Direct-acting control
band
105
PV
PV