Chapter 2
Menu Configuration
2-12
MS-850 Raster Scanner User’s Manual
2–Menu Conf
ig
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User Defined Multidrop
Used when connecting to a concentrator or other device that does not match standard
Multidrop protocol.
Any single character (02 hex to 7E hex) in the ASCII table can be assigned as the
address character. The character chosen is used as the poll character and the subse-
quent ASCII character becomes the select character. For example, if a ^B (02 hex) is
selected as the address, ^C (03 hex) becomes the select address that the host will
use in sending host select commands.
Note
:
Definitions of commands in User Defined and User Defined Multidrop must be
duplicated in host applications to enable poll and select sequences to execute cor-
rectly during transmission.
Note
:
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.
Character Timing
Response Timeout
Default:
12 ms
Options:
0 to 65,000 ms. A zero (0) setting causes an indefinite wait.
Allows you to set the time the scanner will wait before timing out if ACK, NAK, and
ETX are enabled, and a host response is expected.
Intercharacter Delay
Default:
0
. Corresponds to 0 ms displayed in the menu.
Options:
0 to 255. Zero (0) causes no delay between characters.
Allows you to set the time interval in milliseconds between individual characters
transmitted from the scanner 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 character that is transmitted.
LRC (Longitudinal Redundancy Check)
Default:
Disabled
Options:
Disabled, Enabled
An error-checking routine that verifies the accuracy of transmissions. It is the exclu-
sive OR of all characters following the SOM (start of message) up to and including the
EOM (end of message). What this means is that the binary representation of all the
characters in a transmissions are cumulatively added in a column and each resulting
odd integer is assigned a 1 and each even integer a 0 (two 1s = 0, two 0s = 0, a 1
and a 0 = 1). This extra LRC character is then appended to the transmission and the
receiver (usually the host) performs the same addition and compares the results.