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Auxiliary Port
2-10 MS-3 Laser Scanner User’s Manual
2–Communications
Daisy Chain Mode
Definition: In a daisy chain application, scanners are connected in tandem or
“daisy chain” and decoded data is relayed from one scanner to another
on up to the host.
A master scanner has its host port linked to the host computer and its
auxiliary port linked to the host port of the first “slave” scanner in the
chain. Thereafter, each slave’s auxiliary port is linked to the host port of
the slave that is further from the host in the daisy chain.
Each scanner in the daisy chain can be assigned an ID that accompa-
nies any data that it sends.
Usage: Useful in applications where:
A bar code symbol might be scanned in both ladder and picket fence
directions.
A bar code symbol may be present on multiple sides of a package.
Bar code symbols are presented at different depths.
Serial Cmd: <K101,aux port mode,baud rate,parity,stop bits,data bits,daisy chain
ID status,daisy chain ID>
Options: 4 = Daisy chain
Function: Before the master scanner times out, it checks its auxiliary port for
data. It should be set to wait at least 20mS for each slave in the daisy
chain. (See “Timeout Duration” on page 4-17.) If no data is received
within the read cycle timeout, the master sends a noread message to
the host. Otherwise the complete data is sent.
If for example a master scanner is set to timeout in 120mS, the first
slave scanner might be set to 100mS, the next to 80mS, and so forth,
thus assuring that at least 20mS elapses between transmissions.
a
Daisy-chained scanners can send a series of symbols by enabling Mul-
tisymbol and a common multisymbol separator. If the master scanner
does not receive the expected number of symbols, noread messages
are appended to the data string to make up the difference between the
number of symbols enabled in Multisymbol and the number of sym-
bols read.
For example, a master and two slaves have Number of Symbols set to 3
and Multisymbol Separator defined as %. If the master and the first
slave do not find symbols, but the next slave scanner registers a good read,
the transmitted results will be: symbol data % noread % noread.
a. The above example is based on the best case. Other factors such as baud rate, dynamic focus timing, number of
characters in a given symbol, and the number of slaves in the daisy chain can affect timing and may need to be
included in your calculations for complete accuracy.
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