Emerson Rosemount OCX 8800, Instruction Manual

Page: 167 / 306

Instruction Manual
IM-106-880C, OI
Section 7: Foundation
Fieldbus
April 2017
Application
Information
14
1
The MODE parameter is a switch that indicates the target and actual mode of operation. Mode
selection has a large impact on the operation of the PID block:
• Manual mode allows the operator to set the value of the loop output signal directly.
• Automatic mode allows the operator to select a setpoint for automatic correction of
error using the GAIN, RESET, and RATE tuning values.
• Cascade and Remote Cascade modes use a setpoint from another block in a cascaded
configuration.
• Remote Out mode is similar to Manual mode except that the block output is supplied by
an external program rather than by the operator.
• Initialization Manual is a non-target mode used with cascade configurations while
transitioning from manual operation to automatic operation.
• Local Override is a non-target mode that instructs the block to revert to Local Override
when the tracking or fail-safe control options are activated.
• Out of Service mode disables the block for maintenance.
Abrupt changes in the quality of the input signal can result in unexpected loop behavior. To
prevent the output from changing abruptly and upsetting the process, select the SP-PV Track in
Man I/O option. This option automatically sets the loop to Manual if a Bad input status is
detected. While in manual mode, the operator can manage control manually until a Good input
status is reestablished.