What are PI digital states and how do I use them?

Digital states represent non-numeric values in PI — like equipment status (Running/Stopped), alarm states (High/Low/Normal), or system states (I/O Timeout, Shutdown).

Digital State Sets

A digital state set is a named collection of states with numeric codes:

Code	State
0	Stopped
1	Running
2	Faulted
3	Maintenance

Creating Digital State Sets

In PI SMT:

1. Go to Points > Digital States.
2. Click New to create a state set.
3. Add states with codes and names.
4. Save the set.

Using Digital States with Tags

1. Create a PI point with PointType = Digital.
2. Set the DigitalSet attribute to your state set name.
3. The tag will store integer codes but display state names.

System Digital States

PI has built-in digital states for system conditions:

• No Data — no value available
• Pt Created — tag was just created, no data yet
• I/O Timeout — interface lost communication
• Shutdown — PI was not running
• Bad Input — source reported bad quality

In Code

// AF SDK — check for digital state
AFValue val = attribute.GetValue();
if (val.Value is AFEnumerationValue enumVal)
{
    Console.WriteLine($"State: {enumVal.Name}, Code: {enumVal.Value}");
}

Tips

• Use digital states instead of string tags for status values — they're more efficient and searchable.
• Keep state sets small and meaningful (< 20 states per set).
• Document what each state means for operators.