Guidelines for SOVR instructions

Guidelines for SOVR instructions

Use the
Equipment Sequence
 Override (SOVR) instruction to send a HOLD, STOP, or ABORT command to an
Equipment Sequence
, regardless of ownership.
IMPORTANT:
The SOVR instruction is intended for emergencies only. Control Engineers should use caution when deciding to use it.
Keep these guidelines in mind when using the
Equipment Sequence
 Override (SOVR) instruction.
Guideline
Details
Make sure you want to override other owners.
Under most circumstances, use the SCMD instruction to programmatically command an
Equipment Sequence
. However, use the SOVR instruction to command an
Equipment Sequence
 under these conditions:
  • When you are giving the HOLD, STOP, or ABORT command, and the command must always execute under all ownership circumstances.
  • If the HOLD, STOP, or ABORT command must execute even when you have manual control of the
    Equipment Sequence
     through the
    Logix Designer
     application or when another program, such as the
    FactoryTalk Batch
     software, owns the
    Equipment Sequence
    .
Limit execution of the SOVR instruction to a single scan.
Limit the execution of the SOVR instruction to a single scan. Each command applies to only a specific state or states. Once the
Equipment Sequence
 changes state, the command is no longer valid. To limit execution, use methods such as:
  • Run the SOVR instruction within a P1 Pulse (Rising Edge) or P0 Pulse (Falling Edge) action.
  • Place a one-shot instruction before the SOVR instruction.
  • Run the SOVR instruction and then advance to the next step.
Avoid making unnecessary command requests if the
Equipment Sequence
 is generating sequence events.
Unnecessary command requests can flood the event processing buffers and cause you to miss significant events.
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