Allen-Bradley LOGIX 5000 User Manual

Chapter 8
Equipment Sequence
480 Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Keep the following guidelines in mind when using the Equipment Sequence
Command (SCMD) instruction. The SCMD instruction can send the following
commands: START, RESTART, HOLD, STOP, ABORT, and RESET.
Guideline Details
Limit execution of the SCMD instruction to a
single scan.
Limit the execution of the SCMD 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changes state, the command is no longer valid.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 SCMD instruction within a P1 Pulse (Rising Edge) or P0 Pulse
(Falling Edge) action.
• Place a one-shot instruction before the SCMD instruction.
• Run the SCMD instruction and then advance to the next step.
The Equipment Sequence must be owned by
the program to command it.
Both Equipment Sequences and Equipment Phases must be owned to be
commanded. The ownership commands are Attach (SATT)
and Detach (SDET).
Internal sequencers (programs), external sequencers (FactoryTalk Batch),
and operators use an Attach instruction to command an Equipment
Sequence.
See also
Equipment Sequence command (SCMD) on page 473
Equipment Sequence Instructions on page 465
When should I use an SOVR instruction instead of an SCMD instruction?
on page 489
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 the following 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 the following 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.
Guidelines for SCMD
instructions
Guidelines for SOVR
instructions

Allen-Bradley LOGIX 5000 Specifications

General

Brand	Allen-Bradley
Model	LOGIX 5000
Category	Controller
Language	English