User's Guide Part 2

CHAPTER 6 READER-HOST PROTOCOL EXTENSIONS FOR BATTERY POWERED BACKSCATTER TAGS
Using the Commands
This section describes each command, its use and the response formats.
NOTE: Nanoscanner reader commands are case insensitive, that is, you can
use upper or lower case, or any combination thereof, and the reader will
understand the command. Capitalization of commands is used in this document
and in actual command responses is solely for the purpose of readability.
Mask Commands
Mask commands tell the reader which tag to direct further commands to.
G
ET MASK
S
ET MASK
The Get and Set Mask commands will control the current mask that the reader
uses. Masks are important in both addressing tags and interrogating them. In
order to interrogate a single tag, a mask must be set that will single out this tag in
a field. The most commonly used mask in this case would be the entire unique
tag ID. Once this mask has been set, all subsequent commands sent out from
the reader will be listened to and answered only by the one tag that matches the
mask ID. However there may be cases where it is useful to address a number of
tags in the field at the same time. In cases such as these, a mask can be set that
addresses the range of tags of interest, and reader commands can be issued to
all these tags at once. The commands issued in this case can only be used to
direct the tag to perform an operation such as clear its memory or set a
parameter. Commands that require a response from a tag will result in
unpredictable results if multiple tags are trying to answer at the same time.
Mask Example
Set Mask = 4, 0, 00 (4 bit mask, all zeros, starting at bit 0 from left)
All threes tags will respond.
One ‘set’ command will affect all three tags
One ‘get’ command will not work as all three tags will respond at same time
Set Mask = 8, 0, 01 (8 bit mask of 01 starting at bit 0 from left)
Only first tag will respond (0100 0001 0203…)
One ‘set’ command will affect only one tag
One ‘get’ command will work as only one tag will respond
(Also equivalent in this case to Set Mask = 48, 0, 01 00 00 01 02 03 to mask to
entire tag ID)
0100 0001 0203 … 0300 0002 3039 …
0000 0003 4504 …
Three tags in field