Intermec PM23c Fingerprint Developer's Guide (PC23d, PC43d/t, PM23c, PM43, PM4 - Page 64
Background Communication Example, Fingerprint Command, Reference Manual.
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Chapter 4 - Managing Input and Output • COMSET OFF turns off background reception on the specified channel and empties the buffer. • COM ERROR ON enables error handling on a specified channel. • COM ERROR OFF disables error handling on a specified channel (default). • COMSTAT reads the status of the buffer of a specified channel. • COMBUF$ reads data in the buffer of a specified channel. • LOC returns the status of the buffers in a specified channel. • LOF returns the status of the buffers in a specified channel. Background Communication Example This example uses the various Fingerprint commands to set up background communication. For specifics on each command, see the Fingerprint Command Reference Manual. To set up the printer for background communication 1 Enable the error handling for the desired background communication channel using a COM ERROR ON statement. For specifics, see COM ERROR ON in the Fingerprint Command Reference Manual. It may be useful to create a few messages to indicate what caused the interruption. In this example, error handling is enabled for communication channel "uart1:", and messages will be printed to the standard out channel for all conditions that can be detected by a COMSTAT function: 10 COM ERROR 1 ON 20 A$="Max. number of characters" 30 B$="End char. received" 40 C$="Communication error" 50 D$="Attention string received" 2 Continue with a COMSET statement specifying: • the communication channel to be used. • the character or string of characters used to tell the printer to start receiving data and to stop receiving data. • the character or characters to be ignored (filtered out from the received data). • the character or string of characters to use as an attention string that interrupts reception. Note: Start, stop, ignore, and attention characters are selected according to the protocol of the computing device that transmits the data. Non-printable characters, for example STX and ETX can be specified using a CHR$ function. To specify no character, use an empty string. • the number of characters received before the transmission is interrupted. This parameter also decides the size of the buffer (that is, how much of the temporary memory will be allocated). 52 Fingerprint Developer's Guide