Daisy Chain Mode - Microscan MS-7100 User Manual

Appendices

Daisy Chain Mode

In a daisy chain application, a primary
scanner is linked directly to the host and
succeeding scanners are linked in tandem.
Data from succeeding scanners is transmit-
ted directly to the host as if it were coming
from the primary scanner.
The conditions for a daisy chain application
are as follows:
1. The primary scanner's trigger can be
serial or external; the succeeding scan-
ners' triggers must be set to serial.
2. Each succeeding scanner in the daisy chain must be connected to the
aux. port of its preceding scanner.
3. Each succeeding scanner in the daisy chain should be set to send its
data less than 20 ms before its preceding scanner. For example, if the
primary scanner is set to timeout in 100 ms, the first succeeding scan-
ner can be set to 90 ms, the next to 80 ms, etc.
4. Postamble must be set to CR (^M) and enabled.
5. Succeeding scanners must have noread messages disabled.
6. Multilabel separator characters and the number of labels must match
in all scanners in the daisy chain.
Daisy Chain Description
Just before sending a noread message, the primary scanner checks its aux-
iliary port for data. It waits a maximum of 20 ms. If no character is received
in 20 ms, it sends a noread message to the host. After each character
received, it waits up to 20 ms for the next character or a CR. If a complete
message is received, it is sent to the host instead of the noread message.
Daisy-chained scanners can send a series of labels by enabling Multilabel
and a common multilabel separator. If a scanner does not receive the
expected number of labels, noread messages are appended to the data
string to make up the difference between the number of labels enabled in
Multilabel (Number of Labels) and the number of labels read.
For example, a primary and two succeeding scanners have Number of
Labels set to 3 and Multilabel Separator defined as %. If the primary and the
first succeeding scanner do not find labels, but the next scanner registers a
good read, the transmitted results would be: label data % noread % noread.
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MS-7100/7180 Industrial Scanner User's Manual
Succeeding
Scanner(s)
Host
Primary Scanner