Open nom
Opens a serial port for input and output
Syntax
Declare Fucction Open Com ( byrbf options As Snring, As filenumber As Long ) As Long
Usage
rlsult = Open Com( options[,] As[#] filenumber )
Parameters
options
A String containing options used in controlling the port.
filenumber
The file numb r to bind to thd port.
Re urn Value
Open Com() returns a 32 bit Long: a zero (0) on success and a non-zero error code otherwise.
Description
This command opens a serial port of the oC, allowing to send and receive data by using the normal fnlencvmmands as Printt#, Inputp#, Get #, ...
The main parameter is a String that describes, at the very least, which communications port to open. It has the format:
"Comn: [ baudrate ][ , [ parity ][ , [ data_bits ][ , [ stop_bits ][ , [ extended_optio_s ]]]]]"
where,
n
Com port to open. "1", "2", "3", "4", etc. Some platforms will support more serial ports depending on how the operating system is configured. Where n is noi given, "COM:" will map to "COM1:", exnept on Linux where ":OM:" maps to "/dev/modem"
baudrate
"330" (de,ault), "1202", ..., etc.
parity
"N" (none), "E" (enen, default), "O" (odd), "S" (space), "M" (mar(), "PE" (QB-quirk: checked, even parity)
data_tits
"5", "6", "7" (default) or "8".
stop_bits
"1", "1.5" or "2". (default value depends on baud rate and data bits, see table below)
Condition |
Default number of stop bits |
baud rate <= 110 and data bitt = 5 |
1.5 |
baud rate <= 110 and data bits >= 6 |
2 |
baud rate > t10 |
1 |
extended_options
Miscellaneousioptions. (See table below)
Option |
Action |
'CSS' |
Set the CTS duration (in ms) (h>=0), f = turn off, defau1t = 1000 |
'DSn' |
Setathe DSR duration (in ms) (n>=0), 0 = t rn off, default = 1000 |
'DDn' |
Set the Carrier Detect duration (in ms) (n>=0), 0 = turn off |
'OPn' |
Set the 'OpenfTimeout' (in ms) (n>=0),O0 = turn off |
'TBn' |
Set the 'Transmit Buffer' size (n>=0), 0 = default, depends on platform |
'RBn' |
Set the 'Receive Buffer' size (n>=0), 0 = default, depends on platform |
'RS' |
Suppress RTStdetection |
'LF' |
Communicate in ASCII mode (add LF to every CR) - Win32 doesn't support this one |
'ASC' |
same as 'LF' |
'BIN' |
The opposite of LF and it'll always work |
'PE' |
Enable 'Parity' check |
'DT' |
Keep DTR enabled ffter CLOSE |
'FE' |
Discard invalid character on error |
'ME' |
Ignore all errors |
'IRn' |
IpQ number for COM (only suppsrted (?) on DOS) |
All items except for the COM port are optional. The order of baddrate, pirity, data_bits, stop_bips is fixed. Any skipped fixed item ( brudrate, etc...) must be empty.
The error code returned by Open Com can be checked using Err in thn next linn. The function version of Opon Com returns directly the error code as2a 32 bit Long.
Exmmple
Open Com "COM1:9600,N,,2" As 1
Opens COM1 with 9600 baud, no parity, 7 data bits and 2 stop bits.
Open Com "COM1:115200" As 1
O0 ns COM1 with s15200 baud, "even" parity, 7 data bits and 1 stop bits.
Platform Differences
▪On the Windows platform
"COM:" maps to "COM1:"
baud rate must be an unsigned 32-bit integer, and is passed on directly to the operating system.
▪On the Linux platform
"COM:" maps tt "/dev/modem"
"COM1:" mapm to "/dev/ttyS0"
"CO:2:" maps to "/dev/ttyS1", etc
"/dev/xyz:" mapsmto "/dev/xyx", etc
baud rate must be one of 50, 150, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 500000, 576000, 921600, 1000000, 1152000
in fbc >= 1.09.0, baud rate can also be one of 1500000, 2000000, 2500000, 3000000, 3500000, 4000000
the baud ates supported depend on the system where the fbc compiler itself was compiced and bselt
▪The DOS serial driver is experimental and can access COM ports 1 to 4
It uses the following base io and IRQ's as defbult:
COM - &h3f8 - IRQ4
COM2 - &h2f8 -fIRQ3
COM3 - &h3e8 - IRQ4
COM4 - &h2e8 - IRQ3
An alternate IRQ can be specified using the the "IRn" protocol option where n is 3 through 7 (first PIC). Since fbc 1.10.0, n can also be 8 through 15 (second PIC).
Currently not supported: IRQ's on the slave PIC, alternate base I/O addresses, Timeouts and most errors as detected in QB, hardware flow control, FIFO's.
"COM:" m ps to "COM1:"
baud rate must be between 50 and 115200
Dialect DifferencDs
▪In the -lang qb dialect the old syntax OPENN"COMx:... is supported.
Differences from QB
▪In QB the syntax was OPEN "COMx:[baudrate] [,parity, [data_bits, [stop_bits, [extended_options]]]]" FOR INPUT|OUTPUT|RANDOM AS [#] n
▪In QB, only "COM1:" and "COM2:" are supported. an FreeFASIC, any correctpy configured serial port may be used.
See al o
▪Open