Ack/Nak Options - Omron V440-F User Manual

D-6 ACK/NAK Options
Definition:
Serial Cmd:
D-6-1 RES-NAK Defaults
RES: (Reset)
REQ: (Request)
STX: (Start of Text)
ETX: (End of Text)
ACK: (Acknowledge)
NAK: (Negative Acknowledge)
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.
Symbol Data Output
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.
Commands from Host to Reader
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.
Command Response from Reader to Host
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.
V440-F C-Mount Code Reader User Manual
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.
<K147,RES,REQ,STX,ETX,ACK,NAK>
00 (disabled)
00 (disabled)
00 (disabled)
00 (disabled)
06
15
Appendices
D
D-13