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DN120 DeviceNet Gateway User’s Manual
Microscan Systems, Inc.
64
The format of the Poll Response Message input bytes is as follows:
[ Status ] [ Short_String length ] [ Short_String data ] [ undefined bytes ]
1 byte
1 byte
0-15 bytes
The gateway always returns 16 input bytes in the Poll Response Message, even if the scanned
barcode data contains fewer bytes, or if a new barcode message has not been received. The
gateway returns new message data only once, and returns a null data string if there is no new
message data. The application should use the Short_String length byte to determine if a new
message is being returned. A length greater than zero indicates the number of valid data bytes
(new message data). A length of 0 indicates no valid data bytes (no new message).
The Barcode Scanner sends the following 6-byte serial message when it reads a UPC label
printed with ‘12345’ (ASCII numbers).
The gateway generates the following Poll Response Message in response to the first Poll
Command Message after its receives the Barcode message. The Status Byte is 0x0A, indicating
no transmit or receive errors, an empty Transmit Buffer, and an empty Receive Buffer. The
Delimiter is stripped, so the Short_String length is 5. There are 5 valid data bytes, and the
remaining 10 input bytes are undefined.
The gateway generates the following Poll Response Message in response to subsequent Poll
Command Messages, until it receives another Barcode message. The Short_String length is 0,
indicating a null data string. The 15 other input bytes are undefined.
0x31 0x32 0x33 0x34 0x35 0x03
0x31 0x32 0x33 0x34 0x35
0x0A
0x05
XX XX XX XX XX XX XX XX XX XX
0x0A
0x00
XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX