Casio IT-2000W - Manual (Page 214)

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Reception Buffer
This library uses two reception buffers, as shown below, so that during the processing (read) of one
of the received barcodes the next barcode can be successfully received.
Fig. 8.31
The following explains the operation sequence by which codes are put into the reception buffer.
 When the first barcode is received, it will be temporarily stored in Buffer A.
 When the second barcode is received, it will be temporarily stored in Buffer B.
 When the third next barcode is received, it will be temporarily stored in Buffer A.
 When the fourth barcode is received, it will be temporarily stored in Buffer B.
With this library the received barcodes are distributed alternatively to the two buffers as described
above. If one of the received barcodes is not read, it will be overwritten by a new barcode.
This necessitates any received data to be acknowledged with the OBR_Stat function or
OBR_SetUserEvent function, then read using the OBR_Read function after acknowledgment.
Note:
 If programming with this library, first make the OBR_Open function call. The OBR_Open
function will turn on the power supply to the COM port and initialize it. It enables the operation
of other functions (OBR_Send, OBR_Read, etc.) and maintains the power supply to the COM
port. Therefore, always call the OBR_Close function so that the COM port is turned off and
freed before completing the use of the OBR (i.e. application).
 DT-9650BCR and DT-9656BCR are not compatible with each other. The OBR_Send function
will execute necessary processes according to OBR type specified by the OBR_Open function.
Values to be sent to OBR will not be the same for both the OBR models. Refer to each reference.
 DT-9650BCR and DT-9656BCR have an EEPROM in which the setup contents can be written
and stored. This eliminates the need to perform setup each time the power is turned on.
Buffer : A
Buffer : B