Rockwell Automation 1797-OE8H FLEX Ex HART Analog Modules User Manual - Manual (Page 16)

Publication 1797-6.5.3 - March 2006
1-2 About the FLEX Ex HART Analog Modules
How FLEX Ex Analog
Modules Communicate
with Programmable
Controllers FLEX Ex analog I/O modules provide best utility when used with ControlNet
Ex products on the ControlNet network. Data connections are established
between the I/O module and an Allen-Bradley programmable controller to
transfer information between the two at a scheduled rate.
Input module information is then automatically made available in the PLC
data table through the data connection. Reciprocally, output data information
determined by the PLC program is also automatically transferred from the
PLC data table to the output module through the data connection.
In addition, when the data connection is originally established, configuration
information for the module is automatically transferred to it via the network.
Events After Cycling Power
You must apply intrinsically safe +/-V power to your FLEX Ex analog I/O
modules. The following sequence of events occurs after power has initially
been applied to your module:
• The module begins an internal diagnostic check. The channel 0 LED
indicator turns ON to indicate the check has begun. The indicator turns
OFF when the check is finished.
• After the diagnostic check, module configuration information, selected
by the user and downloaded over the network, is applied by the module.
For more information on configuration options, see Chapter 2.
• Following the module configuration download for the 1797-IE8H
module, the module begins producing runtime data for the PLC.
• Following the module configuration download for the 1797-OE8H
module, the module applies configuration data to output channels.
• If any diagnostics or alarms are generated during normal module
operation, the data is returned to the PLC controller.