Instruction manual
Integer Compares
890USE18300 September 2003 59
Greater-than-threshold Integer Compare Block
Summary A greater-than-threshold integer compare block performs a comparison between an
analog input value and a threshold value that you specify using the Advantys
configuration software. The analog input value is represented as an integer in the
range -32 768 to +32 767. The software allows you to assign a delta (∆) value, which
acts as an hysteresis around the threshold value. The action produces a Boolean
result as its output.
Structure of a
Greater-than-
threshold
Compare Block
A block diagram for a greater-than-threshold integer compare is shown below:
The block has two inputs—an enable input and one operational input. The enable
input turns the block on or off. The operational input sends a word value to the block
that will be compared against the threshold.
The block also has two preset values (See Configuring Preset Values for a Reflex
Block, p. 27)—a threshold value against which the operational input value will be
compared and a ∆ for hysteresis around the threshold. You must specify these
presets.
The output is a Boolean 1 when the operational input value is greater than
threshold + ∆ and a Boolean 0 when the input is less than or equal to threshold - ∆.
The output remains unchanged when the operational input is greater than threshold
- ∆ and less than or equal to threshold + ∆.
Enable Input A greater-than-threshold compare block can be enabled either by a Boolean 1 or an
always enabled constant. It can be disabled by a Boolean 0 or an always disabled
constant.
If the enable input is a Boolean, it may be produced by:
a digital input or output from a module on the island
a digital output from the virtual module (See The Virtual Module, p. 28)
an output on the action module (See Using the Action Module as an Input to a
Block, p. 32) written to by the fieldbus master
When the enable input is a Boolean 0 or an always disabled constant, the block is
disabled—the action does not execute and the output is frozen in the state it was in
when the block became disabled. The block continues to process inputs but does
not act on them. If the block becomes enabled, it immediately begins acting on the
latest set of inputs received.
output
enable
operational input
greater than threshold compare
threshold +/-
∆