Bulletin 2755
Single/Dual-Head Enhanced Bar Code Decoders
Product Data
15
Host Message Replacement Rules
Function 5 on the Select Operation menu accesses the Host Message
Replacement Rules configuration screen. Use this function to modify the
message sent to the host.
Rule Status
Each number represents an available host message
replacement rule. Currently enabled rules are
marked with an asterisk ( * ), Rules are enabled by
assigning a value to the Find String Containing field.
Host Message Replacement Rule Definition
Displays the current search rule criteria (Source,
Symbology, Symbol Number, and Find String
Containing) and the replacement string to send to
the host when matches are found. The rule
definition also includes parameters to fix the field
length, character used to “fill” the field, and the
alignment of the string within the field.
Example Testing
Provides a “worksheet” where you can insert
sample bar code strings to test your rules.
Allows you to “debug” your replacement rule
expressions for structural and logical errors
before going on-line. Just input the test bar code
string on the left. The string that appears in the
host message after application of the displayed
rule appears on the right. If your test string does
not create a match, you will be notified of that
fact on the right side of the screen.
Host message replacement rules may not be required in every application.
They are unnecessary when your needs include simple object counting, or
collection of raw bar code data. However, host message replacement rules
will prove useful when you need to substitute a predetermined output
message for specific bar code data during decoding. With them you can:
•
send data in a particular, predefined order regardless of the order in which
the labels were read
•
mask bar code characters to simplify operations and speed processing
•
truncate or pad the length of the data package
•
substitute a predetermined text string for one or more expected values
•
convert abstract bar code contents into more easily understood text form
•
categorize labels based upon selected portions of their contents.
Both the search and replacement strings that make up a Host Message
Replacement Rule can consist of a combination of standard ASCII characters
and special characters known as metacharacters. Metacharacters are used to
perform logic functions on the incoming data string.
