September 2001
S6350 Reader Reference Guide
31
Valid Data & Collision Flags
Valid Data Flags
: This 16-bit field corresponds to whether valid data was received in the 16
possible Time Slots.
Bits
0
to
7
of the
LSB
respectively correspond to
Time Slots
1
to
8
,
while
bits 0
to
7
of the
MSB
correspond to
Time Slots 9
to
16
respectively. A set bit
corresponds to valid data being received in that particular Time slot.
Collision Flags
: This 16-bit field corresponding to whether a collision occurred in the 16
possible Time Slots.
Bits 0
to
7
of the
LSB
respectively correspond to
Time Slots 1
to
8
,
while
bits 0
to
7
of the
MSB
correspond to
Time Slots 9
to
16
respectively. A set bit
corresponds to a collision being detected in that particular Time Slot.
Note:
It is possible to issue the Inventory Command for just 1 Time Slot
instead of 16. In this case, the preceding packet structure is still
valid; the required Valid Data flag and Collision flag reside in bit 0
of the LSB of their respective fields. It follows that issuing the
Inventory Command for a single Time Slot will result in a
maximum of one 80-bit response being returned
If both a Valid Data flag and its corresponding Collision flag are
both clear then this indicates that no transponder was detected for
that particular Time Slot.
Starting from Time Slot 1 and progressing to Time Slot 16, for each
Time Slot where a transponder was successfully read (without
collision), its 80-bit data is appended to the Data section of the
message packet.
