254764-001 Rev B 11
Edge Sync Mode
This mode senses a signal transition level of a sync signal as shown in Figure S1.
Sync sensed here
Figure S1 – Edge Sync
Figure S1 shows the sync operation of an SV unit programmed to sense the rising edge of a sync signal in
edge mode. Each time a rising edge is sensed, the SV unit does the following:
1.
It verifies that at least the number of bar codes expected (programmed) since receiving the last
sync input have been fully decoded. If not, a No Read condition is internally set for possible
reporting through communication or output activation.
2.
It begins a new interval, counting the bar codes analyzed until the next sync input is received.
3.
A Serial communication report is transmitted and an output port is updated per its
programmed function each time a bar code is analyzed.
Envelope Sync Mode
This mode senses two (leading and trailing) transitions of the sync signal to determine when to begin and
end the period for determining missing bar codes as shown in Figure S2 below.
Sync period starts here
Sync period ends here
Figure S2 – Envelope Sync
Figure S2 shows the sync operation of an SV unit programmed to sense the rising voltage edge as the start
of a sync period. The SV unit operates in this mode as follows:
1.
Upon receipt of the starting edge of a sync signal, the unit begins counting the bar codes being
scanned and analyzed.
2.
A Serial communication report is transmitted and an output port is updated per its
programmed function each time a bar code is analyzed.
3.
Counting ceases upon receipt of the trailing edge of a sync signal. The SV 2 Series determines
that at least the number of bar codes expected (programmed) during the sync period have been
fully decoded. If not, an internal No Read condition is set for possible reporting through
communication or output activation.
4.
The SV unit then waits for the next leading edge of a sync signal to begin counting codes
being scanned and analyzed.
NOTE: In either sync mode, for best performance, mount the SV unit in a location where a bar code is
not in the laser beam when an active edge signal is received.
