Contents, cont'd. - Intermec

COMSTAT
Chapter 2 Program Instructions
Field of Application Function reading the status of the buffer of a communication channel.
Syntax COMSTAT()
is one of the following communication channels:
1 = "uart1:"
2 = "uart2:"
3 = "uart3:"
4 = "centronics:"
Remarks This function is closely related to COMSET, ON COMSET GOSUB,
COMSET ON, COMSET OFF, COM ERROR ON/OFF and COMBUF$.
It allows you to find out if the buffer is able to receive background data, or –
if not – what condition has caused the interruption.
The buffer's status is indicated by a numeric expression, which is the sum of
the values given by the following conditions:
• Copy of hardware handshake bit .................................................. 0 or 1
• Interruption: Max. number of characters received ................................ 2
• Interruption: End character received .................................................... 4
• Interruption: Attention string received ................................................. 8
• Interruption: Communication error.................................................... 32
Example A message will appear on the screen when the reception is interrupted by any
of four COMSET conditions being fulfilled:
10 COM ERROR 1 ON
20 A$="Max. number of char. received"
30 B$="End char. received"
40 C$="Attn. string received"
50 D$="Communication error"
60 COMSET 1, "A",CHR$(90),"#","BREAK",20
70 ON COMSET 1 GOSUB 1000
80 COMSET 1 ON
90 IF QDATA$="" THEN GOTO 90
100 END
1000 QDATA$=COMBUF$(1)
1010 IF COMSTAT(1) AND 2 THEN PRINT A$
1020 IF COMSTAT(1) AND 4 THEN PRINT B$
1030 IF COMSTAT(1) AND 8 THEN PRINT C$
1040 IF COMSTAT(1) AND 32 THEN PRINT D$
1050 PRINT QDATA$
1060 RETURN
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