Rockwell Automation 1797-OE8 FLEX Ex Analog Modules User Manual - Manual (Page 24)

Publication 1797-6.5.1 - May 2005
2-8 Understanding Configurable FLEX Ex Analog Module Features
Latch Retry Mode
Latch Mode determines channel operation under wire off or lead break fault
conditions. This feature controls the operation of two channel groups,
channels 0-3 and channels 4-7. Channel detection occurs on a continuous
basis. If a fault is detected, the channel fault alarm is set.
If Latch Mode is enabled when a fault occurs, the fault will remain latched in
its fault state until a Global Reset (see below) is issued. If Latch Mode is
disabled when a fault occurs, the channel reports a fault until the fault is
corrected. Global Reset is not necessary if Latch Mode is disabled.
When using your programming software, set the Latch Mode bit to 0 to
disable the feature. Set the bit to 1 to enable it.
Global Reset
Global Reset works in conjunction with Latch Mode during fault conditions. If
Latch Mode is enabled and a fault condition occurs, the channel operating with
a fault remains in this condition (with analog or digital fault state implied) until
a Global Reset is issued. The Global Reset feature resets all outputs of a
particular channel group to accept normal system output data.
The Global Reset feature is an edge triggered signal. Use your programming
software to set the Global Reset bit to 1 for normal operation. Resetting of
outputs occurs during the 1 to 0 transition.
Analog Digital State
You can configure your FLEX Ex analog I/O modules to work in an analog
mode or digital mode using the Analog Digital State feature. Depending on
which state you choose for your application, additional parameters (see the
descriptions of Analog Fault State and Digital Fault State on page 2-9) must be
configured for your module to react to fault conditions.
Set the Analog Digital State bit in your programming software to 0 for your
module to operate in an analog state. Set the bit to 1 for your module to
operate in a digital state. A selection bit is available to each channel.