4.3        Discrete Tag Properties

A Discrete Tag reads or writes an integer value from a PLC or field device that ranges from 0 to 7.  A Discrete type tag is also referred to as a Digital Tag.    A single bit (or up to 3 bits) in a register or status word is read or written.   Optionally, the tags value can be displayed as a text descriptor, for example ON, OFF, True, False, Run, Stop, Auto, Manual, HOLD, etc.

If three bits are read or written, up to 8 state descriptors are used to display the  'State" of the tag's value.  If a single bit is read or written form the device, then only two state descriptors are used.

The value of the Tag read by calculation tags, accumulation tags, scripts, keymacros and user programs is always the integer representation (0 to 7).  The tag descriptor fields can be read scripts and user programs (DESCR0 to DESCR7).

Discrete Type tags have fewer properties than Analog tags.  Discrete Tag Properties become the Tag Fields associated with Discrete Tags.  For example, State 0 Descriptor becomes the .DESCR0 field for the tag.  For example, LS101.DESCR0 is OFF.