I/O Scans; Alarms - Emerson PACSystems RX3i User Manual

User manual
GFK-2892G
4.1.3

I/O Scans

As shown in Figure 7, there are several I/O Scans that effect how the input and output
devices on the Genius bus exchange data with the RSX3i PLC.
The RX3i scan reads input data from all the devices connected to it and active in its
configuration. It uses this input data to solve the control logic supplied for the application.
At the conclusion of the logic execution, the output data is ready for distribution and the
output portion of the RX3i scan takes place.
The PNC001 PROFINET Controller operates on its own cycle, receiving input data for all
devices connected to it, including the GCG001 Genius Gateway. It passes the input data to
the RX3i during the RX3i input scan. When the RX3i performs its output scan, the output
data configured to the PNC001 is transmitted by the PNC001 to the output devices on its
network, including the GCG001 Genius Gateway.
The GCG001 also operates on its own scan cycle. As the Genius bus token passes from one
SBA to the next, each device on the Genius Bus takes its turn to transmit its input data to the
GCG001, which then makes that input data available to the PNC001. The GCG001 also
consumes all the output data produced by the PNC001 and broadcasts that data to all the
output devices on the Genius bus whenever it receives the Genius Bus token.
All the I/O scans described above are asynchronous and may vary depending on the path
through the RX3i logic, traffic on the PROFINET and traffic on the Genius Bus. Should I/O
update rates be a concern for the application, it would be prudent to perform a worst-case
analysis of the interacting scan cycles.
4.1.4

Alarms

Whenever an alarm condition occurs on a Genius Device, a background message
(datagram) is transmitted from the device to the GCG001. This transmission occurs while
the alarmed device has the Genius Bus token. Upon reception, the GCG001 formulates an
Alarm message to be passed to the PNC001, which in turn passes it to the RX3i CPU. The
RX3i takes appropriate action and notifies the operator per the logic in the application.
Alarms may be cleared programmatically using either the Clear Circuit Fault COMMREQ (see
Figure 35) or the Clear All Circuit Fault COMMREQ, or via the Genius Hand-Held Monitor
(HHM). Note that whenever the HHM is used to clear a circuit fault, the GCG001 will not be
aware of this condition, thus will not have cleared the corresponding fault. Under these
conditions, the Diagnosis Disappears Fault will not have been logged and any subsequent
fault from the same point will not be reported to the I/O Fault Table. Be sure to follow up any
HHM clearing of faults with a COMMREQ to clear the same fault(s) in order to eliminate the
discrepancy described here.
Typically, the field problem needs to be investigated and resolved before the alarm can be
successfully cleared. For the alarm to be cleared, the alarm condition must no longer be
present and the Genius device must receive a suitable background message instructing it to
clear the alarm notification. If the alarm condition is absent, the Genius device will cease to
exhibit the alarm indication (LEDs will operate normally again). If the alarm condition is still
present, a new alarm cycle will be initiated. See Sections 0, 6.4.6 and 6.4.4 for related
COMMREQ or Data_Init_Comm instructions. Refer to Genius I/O System and
Communications User's Manual, GEK-90486-1, for further details.
System Operation
Chapter 4
Sep 2019
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