4-6 Field Control™ Genius® Bus Interface Unit User’s Manual – October 1999 GFK-0825F
4
6 Move Input Data to the Communications Buffer
The BIU then moves all current discrete and analog input values presently in its network map into a
memory buffer, in prepar ation for transmitting them on the Genius bus.
7 Move Output Data from the Communications Buffer
After moving the inputs into the communications buffer, the BIU moves newly-received output
data from the communications buffer. It combines this data with any existing forced discrete output
states and analog values and places the combined data in its discrete (%Q) and analog (%AQ)
output memories, as defined in the BIU I/O map.
If the BIU is not receiving out puts from the bus, it sets mapped ou t put references for convent ional
modules to their default/hold last state conditions, then forces them. For any intelligent module set
up for defaults, the BIU sets ou t put table references to th eir forced state or value, or t o zero.
8 Move Reference Parameters from a Synchronization Module to the BIU
If a module has been configu r ed as a Synchronization modul e, the BIU next moves all configu red
reference parameter data from the module to the BIU's internal memory tables, then applies any
forces. If the Synchronization module is busy, the BIU waits then retries. If the BIU is unable to
move the data after five seconds, it sets its own corresponding memory locations to zero or holds
its last states, as configured for the Synchronization module.
9 Move Group Data from Synchronization Module to BIU
If a module has been configured as a Synchronization module, the BIU moves all its defined group
data to the BIU's internal tables, then applies any forces. If the BIU is unable to read the specified
data, it generates a fault report, and defaults the data to 0 or holds its last states, depending on the
module's configurat ion. If any of the data items are pr esently forced, those for ces ar e retained.
10 Send Outputs to Conventional Modules
The BIU next sends output data to conventional output modules in the I/O station. Discrete output
modules automaticall y echo the received outputs ba ck t o the BIU. If a module fails to ech o it s
outputs the BIU generates a fault report for that module. If the module is configured for output
defaulting, the BIU attempts to set outputs to their default states. This is not always possible,
depending on the nature of th e problem.
For conventional anal og m odules, the BIU converts dat a fr om the selected scaled unit s and
performs ran ge checking be f ore sending th e outputs.
11 Send Reference Parameters to Int elligent Modules
Next, the BIU sends reference parameter data from its tables to intelligent modules except a
Synchronization module. If the BIU is unable to contact a module it generates a fault report.
12 Move Group Data to Intelligent Modu les
The BIU moves group data from intelligent modules or from its own internal memories to any
intelligent modul es , ex cep t a Synchronization modul e, that is configured to receive d ata during that
sweep. If the move fails, a fault is generated.
Background Tasks
After performing all th e data transfers descri bed a bove, the BIU performs a sequen ce of
background tasks such as fault processing, scanning module IDs, an d testing memory.