Note: When in this sync mode, the sync input is a background application. The SV Series will scan, analyze and report on bar codes as they pass through the beam in this mode, regardless if a sync signal is sensed. The presence of a sync signal allows the number of codes expected (programmed) during the sync period to be used for a No Read condition. The absence of a sync signal results in operation similar to the Free Scan Operation described later.
Sync Mode – Stationary Bar Codes
In this mode, a bar code(s) are placed in the beam and held in a known position. A sync input commands the SV Series to turn on the laser beam, perform a programmable number of scans, report the analyses and turn off the laser beam.
A ~SA communication sync command is the most common sync source in this mode.
Note: The SV Series must be programmed for Picket Fence travel orientation in this mode if the bar codes are stationary when being scanned.
No Sync – Free Scan Operation
In this mode, a sync signal is not used and the SV unit scans and analyzes bar codes at random as they pass through the laser beam. As stated in the Sync Input section, this mode is not recommended because it cannot report on missing or undetectable bar codes that can be caused by printer or other system component failures. This mode is most acceptable when the SV Series is used as a bar code decoder only.
It is recommended to use serial communications to a host in this mode for the host to determine missing codes.
If this mode is used, the SV Series can still detect many print errors because of its partial decode analysis capability. This algorithm can detect a bar code start or stop character and two adjacent characters. This part of a code is usually present in most print failure situations.
For maximum reliability for partial decode analysis, the bar code(s) being analyzed must be present in the laser beam for 10 scans (example: 100 milliseconds for SV units with 100 scans/analyses per second performance). To calculate bar code travel speed in this mode, see "Bar Code Travel Speed Considerations" on page
Parameters Analyzed
For each bar code scanned and analyzed, the SV Series performs practically all the ISO, traditional and laser based verification methods documented in industry specifications. All analysis parameters for these methods are reported via serial communications (see "Serial Port Transmission Format" on page
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