ABB Symphony Harmony Series, Instruction, Page: 185 / 402

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Labels
Channel Label
A channel label identifies an I/O channel of an I/O block. A
channel label can be any unique, meaningful label desired.
The label assignment is optional and is not required for proper
operation. It is strictly for ease of recognition during configura-
tion and maintenance.
A human system interface such as a Conductor work station
and other system nodes use a tag to acquire information from
an exception reporting block and to perform process control. If
desired, the channel label can be defined the same as a tag
name in the system tag database. This allows easily identifying
the relationship between an I/O block point and a tag in the
system tag database.
NOTE: Currently, tag names are limited to 14 characters whereas channel
labels can be up to 32 characters.
Duplicate Labels
Duplicate device labels on the same Hnet are not permitted.
The Harmony controller checks for any duplicate device labels
and will identify any occurrence as a configuration error. It
does not check for duplicate channel labels however. The fol-
lowing paragraphs provide more detail about what occurs
when a duplicate label is detected during configuration, star-
tup, and normal operation.
NOTE: Both I/O modules of a redundant block share the same device label.
These are not seen by the controller as duplicate labels.
Configuration
If the controller configuration contains two or more device def-
inition function codes (FC 221) with identical device labels
assigned, the controller will enter error mode and display a
duplicate label error on its LEDs.
Initial I/O System
Startup
The following occurs when duplicate device labels are detected
on initial I/O system startup:
1. The offending I/O blocks will display a duplicate label error
code (status LEDs 2, 4, and 5 on).
2. A status report indicating bad status is issued for each I/O
block that has a duplicate label. This status indication can be
seen in the controller status bytes.