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Signals

A signal is a named value in a project: a measurement, a state, a setpoint or a command. Drivers read and write signals, screens show them, and alarms and scripts use them.

Names​

A signal name is a path of segments separated by dots, for example Line1.Pump1.Status. Folders form the first segments, and the signal is the last one.

  • A new segment starts with a letter or _ and contains only letters, digits and _, up to 64 characters.
  • The full name can be up to 255 characters.
  • Names are case-sensitive: Pump1 and pump1 are different signals.
  • Spaces and empty segments (two dots in a row) are not allowed.

Names created earlier may also contain -; YTCC keeps them, but new names cannot use it.

Reserved roots​

Three root names belong to YTCC and cannot be used for your own signals: System, Alarms and Session. They hold read-only signals that YTCC fills in itself:

  • System: server time, server and disk state, project, process, driver and history status.
  • Alarms: alarm counters, in total and per area and group.
  • Session: the signed-in user and the client. These values are kept per browser and cannot be written.

The rule applies to whole segments only, so a name such as SystemA.Level is allowed.

Data types​

A signal has one of 14 data types. The interface groups them into families:

FamilyData types
BitBit
IntegerInt8, Int16, Int32, Int64
Unsigned IntegerUInt8, UInt16, UInt32, UInt64
RealFloat32, Float64
TextText
Date/TimeDate/Time
EnumEnum

Signal types and instances​

A signal type describes a group of signals that belong together, such as the status, speed and fault signals of a pump, with default settings for each. When you apply a type to a folder, the folder becomes an instance of the type and each element of the type becomes a signal in it.

The signals of an instance take their settings from the type, field by field. When you change a field on one signal, that signal keeps your value, and later changes to the type no longer overwrite it.

Old names after a rename​

When you rename a signal or a folder, YTCC remembers the old name. Screens and server scripts that still use the old name keep working. The old name stays in use until you remove it with Remove old name; until then you cannot give the old name to another signal. Once you remove it, expressions, scripts and screens that still use the old name no longer find the signal and show no value, so change them to the new name first.

Units​

The unit of a signal is a label of up to 32 characters, such as bar or °C. YTCC shows it next to values and in alarm texts. It does not convert values between units.