Symbol SE 923, Integration Manual

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SE-923 Scan Engine Integration Guide
This message is sent when the received packet fails the checksum verification or some error
occurred while handling the message.
Note: ACK/NAK handshaking can be disabled. We recommend, however, it
be left enabled.
It is not necessary to respond to a valid ACK or NAK message.
NAK types supported by the SE-923 are contained in Table 6-5.
The decoder only resends a message twice. If the message has not been sent successfully at
that time, the decoder declares a transmit error, and issues transmit error beeps (LO-LO-LO-
LO).
Table 6-5. Decoder-Supported NAK Types
NAK Type Meaning Receiver Action
NAK_RESEND Checksum incorrect. Ensure checksum is correct. Limit
number of resends. Send packet
again with resend bit set.
NAK_DENIED Host is unable to comply with
the requested message (e.g., beep
code is out of range). Do not send data with this message
again. Developer should check
values with specified values.
Developer should ensure the proper
character is sent, if using wake-up
character.
NAK_BAD_CONTEXT Host does not recognize the
command.