Schneider Electric 890USE17700 - Manual (Page 157)

Advanced Configuration Features
890USE17700 April 2004 157
Configuring a
Reflex Action Each block in a reflex action must be configured using the Advantys configuration
software.
Each block must be assigned a set of inputs and a result. Some blocks also require
that you specify one or more user-preset values—a compare block, for example,
requires that you preset threshold values and a delta value for hysteresis.
Inputs to a Reflex
Action The inputs to a reflex block include an enable input and one or more operational
inputs.The inputs may be constants or they may come from other I/O modules on
the island, from virtual modules or outputs from another reflex block. For example,
an XOR block requires three inputs—the enable and two digital inputs that contain
the Boolean values to be XORed:
Some blocks, such as the timers, require reset and/or trigger inputs to control the
reflex action. The following example shows a timer block with three inputs:
The trigger input starts the timer at 0 and accumulates time units of 1, 10, 100 or
1000 ms for a specified number of counts. The reset input causes the timer
accumulator to be reset.
An input to a block may be a Boolean value, a word value, or a constant, depending
on the type of reflex action it is performing. The enable input is either a Boolean or
a constant always enabled value. The operational input to an block such as a digital
latch must always be a Boolean, whereas the operational input to an analog latch
must always be a 16-bit word.
You will need to configure a source for the block’s input values. An input value may
come from an I/O module on the island or from the fieldbus master via a virtual
module in the NIM.
Note: All inputs to a reflex block are sent on a change-of-state basis. After a
change-of-state event has occurred, the system imposes a 10 ms delay before it
accepts another change of state (input update). This feature is provided to
minimize jitter in the system.
enable
result
operational input 1
operational input 2
XOR
result
enable
trigger
timer
reset
time unit x terminal count