Manual

48 Publication LOGIX-UM001B-EN-P - April 2010
Chapter 3 Guidelines
Equipment Interface Tag
Guidelines
An equipment interface tag links an equipment phase to an equipment
program.
• The equipment phase uses the tag to configure and command the
equipment program.
• The equipment program uses the tag to report its status or condition.
Equipment Phase
Directs the actions of the
equipment (what to do and
when)
• produce product
• stop producing product
• add water to a tank
• wait for the operator to do
Equipment Program
Does the actions for a specific
group of devices (does it)
• jog axis
• run pump
• open valve
• calculate control variable
Interface Tags
Links equipment phase to
equipment program
• jog at this speed
• go to the 1 state (run
pump)
• axis is jogging
• valve is faulted
You are here.
Guideline Details
List the values that your equipment phase
must give to the equipment program or get
back from it.
Think of these values as a faceplate to the equipment program. It is the values that your
equipment phase uses to control and monitor the equipment program. Do not include I/O
data.
Inputs to the equipment program Outputs from the equipment program
• mode requests
• set points
• commands such as on, off, start,
stop, reset
• permissives
• overrides
• mode status
• control values
• done or completion
• alarms
• faults
• health indication
• totals or accumulated values
Create a user-defined data type A user-defined data type lets you make a template for your data. It lets you group related
data into a single data type. You then use the data type to make tags with the same data
lay-out.
If you have more than one equipment phase, lay out the data type so that it’s easy to use
with more than one equipment phase. Consider the following:
• Include a range of data that makes the data type more versatile.
• Use names that are as general as possible.
Example: The name State_Cmnd lets you use it for any equipment that runs in 2
states like on/off, running/not running, pumping/not pumping. It is easier to re-use
than names such as Open or Close. Those names apply to valves but not pumps or
motors.