ACK / NAK Options

Definition:	These parameters take effect for ACK/NAK <K140,4> on the main RS-232 or RS-422 ports (not on the Auxiliary Port), and are completely independent of the Polling Mode Options <K148>. The Imager 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>

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

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 Imager

TX to Imager: [STX] <command> [ETX] [LRC]

Response from Imager: ACK/NAK. Sent when LRC, ETX, or command-ending angle bracket `>' are received, depending on what is enabled.

Command Response from Imager 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 Imager 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 USB HID Interface for protocol information relating to USB.