Rockwell Automation 1794-OF8IH FLEX Isolated Input/Output HART Analog Modules - Manual (Page 56)

Publication 1794-UM065B-EN-E - September 2010
44 1794-IF8IH and 1794-OF8IH Configuration
This does not disable the module from gathering HART Command 3
information from the HART Field device. As such, HART Command 3
information from the HART Field device is still available via an unconnected
message to the module.
When the adapter powers up, it reads each module to find out which modules
are present in the Flexbus. For EDT modules it reads Assembly 125 to gain
knowledge of all the assemblies the module has, whether they are
EDT/CEDT and whether they are GET/SET. If an assembly is a CEDT
assembly, the adapter automatically creates a CEDT entry and drops it into the
EDT machine to gather/send this assembly and store the assembly locally in
the adapter. Sometime later a ForwardOpen configuration arrives by the
network for the module. The adapter proxy strips off a portion (Configuation
Part 1) and sends the rest (Configuration Part 2) on through EDT to the
module. Within this module configuration part are the CMD3 Disable Chx
bits. These bits instruct the module to include or not include CMD3 scanning
in the work for the channel. Users may not have HART devices on every
channel so some channels may want CMD3 disabled. If scanning is disabled,
the module also disables the adapter from including that particular associated
assembly in the CEDT scanning routine by the method described below.
The module uses the CMD3 Disable Chx bits to adjust the CEDT entries in
Assembly 125. Initially the Assembly 125 CEDT assemblies (46-53) are
identified as CEDT (0xC0 Cyclic EDT Get or 0x40 Cyclic EDT Set). This
causes the adapter to add them to the CEDT scan. If the module receives a
configuration with CMD3 Disable CHx bits set to "1" (disable), the module
changes the appropriate channel's Assembly 125 entry from 0xC0 Cyclic EDT
Get to 0x80 EDT Get or 0x40 Cyclic EDT Set to 0x00 EDT Set.
Whenever the adapter receives a ForwardOpen to an EDT module, the
adapter automatically rereads the module's Assembly 125 to gain a new view of
the assemblies. This reread is to check for any changes of CEDT Assemby
status to EDT status. If a CMD3 Disable Chx was received on any particular
channel, now the previous CEDT assembly is marked as an EDT assembly
and the adapter will not add that assembly to his CEDT scan. This
ForwardOpen reread will happen any time a module receives a ForwardOpen,
including a Null-ForwardOpen received during system runtime.
Range: 0 = enabled, 1 = disabled
Default: 0