PSC SP400rf, Programming Manual

Page: 86 / 112

G
ENERAL
F
EATURES
80
SP400RF Programming Guide
W
HEN
T
O
A
CKNOWLEDGE
The SP400RF allows you to select the point at which the Base Station will
acknowledge messages from the scanner. An "Acknowledge" is a re-
sponse from the Base Station to the scanner with an ACK, WACK, NAK, or
no response (see
Communications Protocol at the start of this section for a
definition of these terms). "When to Acknowledge" has three options:
Option
①
- The Base Station acknowledges the receipt of a message from
the scanner after the message is checked.
Option
➁
- The Base Station acknowledges receipt of a message from the
scanner after the Base Station sends the last byte to the host
Option
➂
- The Base Station acknowledges receipt of a message from the
scanner after CTS (RS-232 only) is enabled from the host.
R
ADIO AND
I
NTERFACE
L
AYERS
(S
OFTWARE
)
For the radio layer to validate a message, the transmission from the
scanner to the Base Station is checked. (For example, CRC calculation,
header format, correct number of bytes, etc.) For the interface layer to
validate a message, the message from the radio layer is checked to ensure
it is a valid label for a selected interface option.
S
CANNER
A
UDIBLE
R
ESPONSES
Once the scanner reads a barcode, it will produce a "Good Read" beep
immediately. If the scanner does not receive a response from the Base
Station within a programmed period of time after the label is read, the
scanner will emit a "Bad Transmission" indication
1
for the second beep. If
the Base Station determines that the message is not a valid label for the
interface, or the Base Station has been told via host commands or host
handshaking to disable scanning, Base Station will send a NAK to the
scanner. The scanner will then sound a "NAK from the Base" indication
1
for the second beep. When any of the "When to Acknowledge" options
are enabled, the Base Station will send an ACK to the scanner, causing it
to sound an "ACK from the Base" indication
1
.
1 Scanner beep indications are defined later in this section under the "When to Beep"
Options heading.