Honeywell Series 8 I/O - Reducing I;O Link Traffic; Event Collection; PV and Back Calculation Scanning; Table 7 I;O Parameters Scanned When the IOM Is Loaded

2. Series 8 I/O Planning and Design
2.7. I/O Link performance specifications
R500 Series 8 I/O User's Guide 37
April 2017 Honeywell
Block names
Data processing
Link Units per
cycle time
Cycle time
Pulse width modulation for
DOCHANNEL
BACKCALC Scanning
1
IOM block's
SCANRATE
Pulse width modulation for
DOCHANNEL
OP Store
1
OP connector's CM
Execution Rate
Digital Input Pulse
Accumulation IOM Blocks
PV Scanning and
AVRAW Scanning
6.85
IOM block’s
SCANRATE
Reducing I/O Link traffic
If I/O Link overruns persist, you reduce the I/O Link traffic by performing the following:
 Increasing the value of the IOM's Scanning Rate parameter [SCANRATE]
(that is, increasing the time interval between IOM scans)
 Increase the Execution Period of Control Modules containing Output Channel blocks
 Reducing the number of IOMs configured
 Split the IOMs across multiple IOLINKS
 Check for presence of an address “Chattering ” alarm events
TIP
Link IDs are only detected on their corresponding modules.
 Modules with Link ID 1 cannot detect Link ID 2.
 Modules with Link ID 2 cannot detect Link ID 1.
Event collection
Under normal conditions, every IOM configured on the I/O Link, whether primary or
secondary, uses Link Units for event collection. This activity is periodic and can be
accounted for, however; conditions in which numerous events and alarms are generated
are unpredictable and may cause transient I/O Link overruns and delays in display
updates. These transient overruns clear once the rush of events and alarms are collected.
PV and Back calculation scanning
The following I/O parameters are automatically scanned by the C300 as soon as the IOM
block is loaded.
Table 7 I/O parameters scanned when the IOM is loaded