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The LOC function returns the status of a serial (COM) port received buffer or the current byte position in an open file.


bytes% = LOC(fileOrPortNumber%)

  • fileOrPortNumber% is the number used in the port OPEN AS statement.
  • Returns 0 if the buffer is empty. Any value above 0 indicates the COM port has received data.
  • Use it in conjunction with INPUT$ to get the data bytes received.
  • Can also be used to read the current position in a file routine. See SEEK.


Example: Reading and writing from a COM port opened in Basic.

OPEN "COM1: 9600,N,8,1,OP0" FOR RANDOM AS #1 LEN = 2048 ' random mode = input and output DO: t$ = INKEY$ ' get any transmit keypresses from user IF LEN(t$) THEN PRINT #1, t$ ' send keyboard byte to transmit buffer bytes% = LOC(1) ' bytes in buffer IF bytes% THEN ' check receive buffer for data" r$ = INPUT$(bytes%, 1) ' get bytes in the receive buffer PRINT r$; ' print byte strings consecutively to screen" END IF LOOP UNTIL t$ = CHR$(27) 'escape key exit CLOSE #

See also

Keyword Reference - Alphabetical
Keyword Reference - By Usage
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