Rockwell Automation 2755 AtomScan Bar Code Reader - Manual (Page 52)

5–7 Configuring Your Reader
Publication 2755-6.9
N ote: Definitions of commands in User Defined and User
Defined Multidrop must be duplicated in host applications to
enable poll and select sequences to execute correctly during
transmission.
Typically, parameters in User Defined Multidrop are defined by
first enabling Multidrop, then enabling User Defined Multidrop.
This pre-loads Multidrop characters into the parameters. You
then change individual characters to match the host or other
requirements.
•
Preamble. Allows you to define a one or two character data
string that can be added to the front of the decoded data. For
example, a carriage return and line feed would display each
decoded message on its own line.
•
Preamble. Allows you to enable or disable the preamble
character(s).
•
Postamble. Allows you to define a one or two character data
string that can be added after the decoded message.
•
Postamble. Allows you to enable or disable the Postamble
character(s).
•
Longitudinal Redundancy Check (LCR). An error-checking
routine that verifies the accuracy of transmissions. It is the
exclusive OR of all characters following the SOM (start of
message) up to and including the EOM (end of message).
•
Response Timeout. Allows you to set the time the reader will
wait before timing out if ACK, NAK, and ETX are enabled, and a
host response is expected.
•
Intercharacter Delay. Allows you to set the time interval in
milliseconds between individual characters transmitted from the
reader to the host. A high setting will significantly slow down
communications. For example, a 200 setting will result in a 1/5
second delay between each transmitted character.
Host Port Parameters
•
Baud Rate. Allows you to set the number of bits transmitted per
second.
•
Parity. Allows you to select an error detection routine in which
one data bit in each character is set to 1 or 0 so that the total
number of 1 bits in the data field is even or odd.
•
Stop Bits. Allows you to select the last one or two bits in each
character to indicate the end of the character.
•
Data Bits. Allows you to establish the total number of bits in
each character.