Hand Held Products 2020, User Manual

Page: 49 / 280

2020/4820/4820 i User’s Guide 2 - 19
Host ACK Selection
Some applications require that the host terminal (or server) approve or reject
incoming barcode data and notify the operator of these actions. These
applications require that the host maintain control over the response indicators
emitted from the source image scanner. Turning the Host ACK selection on,
configures the cordless system image scanners to respond to commands from
the host system.
The following criteria must be met for the Host ACK to work correctly:
• The cordless system must be configured for Host Port RS-232 (terminal ID =
000) or USB COM Emulation (terminal ID = 130).
• RTS/CTS is defaulted off. You must enable it if the host system requires it.
• Host ACK must be enabled ( page 2-20 ).
• System performance degrades when using Host ACK at rates lower than
9600.
• The host terminal software must be capable of interpreting the barcode data,
make decisions based on the data content, and send out appropriate escape
commands to the source image scanner.
Escape commands are addressed to the source image scanner via “Application
Work Groups.” Once a command is sent, all image scanners in a group respond
to that command. Because of this situation,
it is recommended that each
image scanner is assigned to its own group in host ACK mode .
The commands to which the image scanner responds are listed on page 2-21 .
The <ESC> is a 1B in hex. A typical command string is y <ESC> x, where “y” is
the application work group number, “<ESC> x” is the escape command, and the
comma is the terminator, which is required.
Commands may be strung together to create custom response sequences. An
example of a command string is listed below.
0<ESC>4<ESC>5<ESC>6,
The above example will make an image scanner in application work group zero
beep low
, medium, high.
Once Host ACK is enabled, the system works as follows:
• The image scanner reads a code and sends data to the base/host system. No
audible or visual indication is emitted until the image scanner receives an
escape command. The image scanner read illumination goes out upon a
successful read.
• Image Scanner operation is suspended until 1) a valid escape string is
received from the host system (via the base) or 2) the image scanner “times
out.”
• Once condition 1 or 2 above has been met, the image scanner is ready to
scan again, and the process repeats.
Time out is indicated by three rapid beeps at the same pitch. A time out occurs
if the source image scanner does not receive a valid escape command in 10
seconds. If a time out occurs, the operator should check the host system to
understand why a response to the image scanner was not received.