Allen-Bradley MicroLogix 1200 Reference Manual page 254

19-12 Process Control Instruction
Publication 1762-RM001C-EN-P
Automatic / Manual (AM)
Tuning Parameter Address
Descriptions
AM - Automatic/Manual PD10:0/AM
The auto/manual bit can be set or cleared by instructions in your ladder
program. When off (0), it specifies automatic operation. When on (1), it
specifies manual operation. In automatic operation, the instruction
controls the control variable (CV). In manual operation, the user/control
program controls the CV. During tuning, set this bit to manual.
Output limiting is also applied when in manual.
NOTE
Control Mode (CM)
Tuning Parameter Address
Descriptions
CM - Control Mode PD10:0/CM
Control mode, or forward-/reverse-acting, toggles the values E=SP-PV and
E=PV-SP.
Forward acting (E=PV-SP) causes the control variable to increase when
the process variable is greater than the setpoint.
Reverse acting (E=SP-PV) causes the control variable to decrease when
the process variable is greater than the setpoint.
PV in Deadband (DB)
Tuning Parameter Address
Descriptions
DB - PV in Deadband PD10:0/DB
This bit is set (1) when the process variable is within the zero-crossing
deadband range.
Data Format Range Type
binary (bit) 0 or 1 control
Data Format Range Type
binary (bit) 0 or 1 control
Data Format Range Type
binary (bit) 0 or 1 status
User Program
Access
read/write
User Program
Access
read/write
User Program
Access
read/write