Omron V440-F, User Manual

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D-13
Appendices
V440-F C-Mount Code Reader User Manual
D-
6 ACK
/NAK
Opt
ion
s
D
D-6-1
RES-NAK Defau
lts
D-6 ACK/NAK Options
The following are general outlines of the
ACK/NAK
protocol. Items that are framed by brackets (
[ ]
)
can either be disabled or enabled. LRC does not include STX, but it does include preamble, postamble,
and ETX.
TX to host:
[STX] [preamble] SYMBOL DATA [postamble] [ETX] [LRC]
Response from host:
ACK/NAK. Sent when LRC, ETX, postamble, or timeout (waiting for more data)
are detected (if REQ is disabled) depending on what is enabled.
TX to Reader:
[STX] <command> [ETX] [LRC]
Response from Reader:
ACK/NAK. Sent when LRC, ETX, or command-ending angle bracket ‘
>
’ are
received, depending on what is enabled.
TX to host:
[STX] [preamble] COMMAND RESPONSE DATA [postamble] [ETX] [LRC]
Response from host:
ACK/NAK. Sent when LRC, ETX, postamble, command-ending angle bracket
‘
>
’, or timeout (waiting for more data) are detected, depending on what is enabled.
As with
Polling Mode <K140,5>
, the reader can optionally perform the REQ and RES event
sequences in ACK/NAK mode. If the sender does not receive an ACK or NAK, it will send REQ to
request such a response (if enabled). When the sender receives an ACK, too many NAKs, or times out
(if already enabled), it will send a RES (if enabled) to terminate the transaction.
Note:
See
ACK/NAK Data Flow Examples
for sample ACK/NAK communication scenarios.
Definition:
These parameters take effect for
ACK/NAK <K140,4>
on the main RS-232
port and are completely independent of the
Polling Mode Options <K148>
.
The reader always follows the protocol in both directions (to and from the
host). There is no option to disable it from either direction.
Serial Cmd:
<
K147, RES,REQ,STX,ETX,ACK,NAK
>
D-6-1 RES-NAK Defaults
RES: (Reset)
00 (disabled)
REQ: (Request)
00 (disabled)
STX: (Start of Text)
00 (disabled)
ETX: (End of Text)
00 (disabled)
ACK: (Acknowledge)
06
NAK: (Negative Acknowledge)
15
Symbol Data Output
Commands from Host to Reader
Command Response from Reader to Host