Difference between revisions of "OPEN COM"

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::''Syntax:'' [[OPEN]] "COMn: Speed, Parity, Bits, Stopbit, ['''Options''']" FOR mode AS #f LEN = bytesize
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::''Syntax:'' [[OPEN]] "COMn: Speed, Parity, Bits, Stopbit, ['''Options''']" FOR mode AS #P LEN = bytesize
  
 
   
 
   
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* Note: If random use [[LEN]] = to set size of random buffer(default LEN = 128). Use multiples of 128 for larger buffers.
 
* Note: If random use [[LEN]] = to set size of random buffer(default LEN = 128). Use multiples of 128 for larger buffers.
 
* OPEN AS number can use a [[FREEFILE]] value. Numbers used by files already open '''cannot''' be used by OPEN COM!
 
* OPEN AS number can use a [[FREEFILE]] value. Numbers used by files already open '''cannot''' be used by OPEN COM!
* NOTE: NT or XP computers need a program like [http://www.beyondlogic.org/porttalk/porttalk.htm PortTalk] to access COM or other ports!
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* NOTE: NT or XP computers need a program like [http://www.beyondlogic.org/porttalk/porttalk.htm PortTalk] to access COM or other ports with Qbasic only!
  
  

Revision as of 06:24, 8 October 2010

The OPEN COM statement is used to access a computer's Serial port COM1 or COM2 address using an OPEN statement.


Syntax: OPEN "COMn: Speed, Parity, Bits, Stopbit, [Options]" FOR mode AS #P LEN = bytesize


  • QB64 can open any COM port number. Qbasic could only open COM1 or COM2.
  • See Windows System Components list for COM port numbers and port addresses.
  • Four commas are required after the Speed, Parity, Bits, and Stopbit, even if no other Options are used.
  • Speed(baud rate): 50, 150, 300, 600, 1200, 1800, 2400, 9600, 19200 or 115200 maximum.
  • Parity: N (none), E (even), O (odd), S (space) or M (mark). Note: If 8 bits use parity N for numerical data!
  • Bits = number of bits/byte: Valid numbers: 5, 6, 7 or 8
  • Stopbit = number of stop bits: Valid numbers: 1, 1.5 or 2
  • Other OPEN options are optional and in any order separated by commas within the OPEN command string.
Additional Options
* ASC : ASCII byte mode. End of line = CHR$(13). End of file = CHR$(26)
* BIN : Binary byte mode. Default mode if ASC is not used(option not required).
Below m is the timeout in milliseconds 1 to 65535. Zero is ignore timeout. Default m = 1000 :
CDm : Time until timeout of DCD (Carrier Detect) line in. CD0 ignores timeouts.
CSm : Time until timeout of CTS (Clear to Send) line in. CS0 ignores timeouts.
DSm : Time until timeout of DSR (Data Set Ready) line in. DS0 ignores timeouts.
OPm : Time until data lines become active. If timeout then OPEN fails! OP0 ignores timeouts.
If any timeouts occur the OPEN will fail or port access will stop!
RBs : Size of receive buffer when used. Default when not used = 512 bytes
TBs : Size of transmit buffer when used. Default when not used = 512 bytes
RS : Supress detection of RTS (Ready to Send) line. No timeout.




Example: Opening COM port 1 with the OP0 no line timeout option and setting the receive and transmit buffer size using LEN =.

OPEN "COM1: 9600, N, 8, 1, OP0" FOR RANDOM AS #1 LEN = 2048 ' input and output buffersize


See also:

INPUT$, LOC, INKEY$, PRINT #, OPEN




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