Set the parameters needed to communicate with a
serial port. This must always be done before you can send and receive
data through the port.
To configure the communication parameters, use keywords
from the following table to specify the Comfunc as well as a suitable
value chosen from the range applicable to the Comfunc parameter
you want to set. If an error occurs when attempting to set a parameter,
PowerBASIC sets the ERR
system variable to indicate the error number. While each parameter
must be set individually, it is also possible to change certain parameters
without the need to close and re-establish communications.
|
Comfunc |
value
(TRUE <> 0, FALSE
= 0) |
|
BAUD |
Port Baud Rate (9600, 14400, 19200, etc).
See notes below. |
|
BREAK |
TRUE/FALSE Break is asserted. Break is generally
used to "get the attention" of the connected modem, terminal
or system. |
|
BYTE |
Number of bits per byte (4, 5, 6, 7, or 8). |
|
CD |
TRUE/FALSE Carrier Detect state; synonym for RLSD
(READ-ONLY). When CD is TRUE, the DCE (modem) has a suitable
connection on the communications channel present. When CD is FALSE,
there is no suitable connection. |
|
CTSFLOW |
TRUE/FALSE
Enable CTS output flow control (Input signal). When CTSFLOW is enabled, it causes the DTE (computer)
to stop sending data whenever
the CTS signal is set to logic
low by the DCE (modem). Transmission continues when the DCE (modem)
sets the CTS signal back to logic high. The CTS signal is usually
used in response to an RTS signal. |
|
DSRFLOW |
TRUE/FALSE
Enable DSR output flow control (Input signal). When DSRFLOW is enabled, it causes the DTE (computer)
to stop sending data whenever
the DSR signal is set to logic
low by the DCE (modem). Transmission is enabled when the DSR signal
returns to logic high. The DSR signal is often used in conjunction
with CTS in response to a RTS signal. |
|
DSRSENS |
TRUE/FALSE Enable DSR sensitivity. When DSRSENS
is enabled, data received by the DTE (computer) is placed into the receive buffer only if DSR is set
to logic high. If DSR is set low, received data is discarded.
Enabling DSRSENS allows DSR to enable or disable the DTE (the computer)
to receive data from the DTE (the modem). DSRSENS is rarely used
in practical communications situations. |
|
DTRFLOW |
TRUE/FALSE
Enable DTR handshaking flow control (Output signal). When DTRFLOW is enabled, it signals that the DCE (modem)
should prepare to connect to the communications channel. DTR is
usually used for modem on-hook/off-hook control, but can also be used
in conjunction with DSR for handshaking. |
|
DTRLINE |
TRUE/FALSE Enable DTR line. When enabled,
DTRLINE leaves the DTR line active when the port is closed by the DTE
(computer). This ensures that the DCE (modem) does not close the
communications channel when the port is closed. |
|
NULL |
TRUE/FALSE Null ($NUL) bytes are discarded when
read. |
|
PARITY |
TRUE/FALSE Enable parity
checking. This mode must be enabled for the other Parity options
to be selected. |
|
PARITYCHAR |
Character to use for parity error replacement.
PARITY must be enabled. |
|
PARITYREPL |
TRUE/FALSE Enable character replacement on parity
error. PARITY must be enabled. |
|
PARITYTYPE |
0 = None, 1 = Odd, 2 = Even, 3 = Mark, 4 = Space.
PARITY must be enabled. Default = 0. |
|
RING |
TRUE/FALSE Ring indicator is on (READ-ONLY).
When RING returns TRUE, a ringing signal is being received on the communications
channel (by the modem). RING approximates the state of the ringing
signal; however, it may not be reported accurately on all Windows platforms. |
|
RLSD |
Receive-line-signal-detect (READ-ONLY).
See CD/Carrier Detect above. |
|
RTSFLOW |
Ready To Send (Output signal). 0 = Disable,
1 = Enable, 2 = Handshake, 3 = Toggle. Toggle is used for
half-duplex (2-wire) operations to "reverse" the line.
While the DTE (computer) is busy sending data, it raises the RTS signal
and the DCE (modem) blocks its data receive channel. When RTS signal
reverts to logic low, the DCE (modem) reverts to transmit mode and the
DTE (computer) switches to receive mode.
Handshake mode
causes the DTE (computer) to check the receive buffer (RXQUE) after each
character is placed into the buffer. When the buffer is 5/6th full,
the RTS signal is dropped. When the receive buffer drops to below
1/6th full, RTS is raised again. |
|
RXBUFFER |
Size of the receive buffer in bytes. |
|
RXQUE |
Characters currently in the receive buffer (READ-ONLY). |
|
STOP |
0 = 1 stop bits, 1 = 1.5 stop bits, 2 = 2 stop bits. |
|
TXBUFFER |
Size of the transmit buffer in bytes. In some
cases, Windows may not be able to report the transmit size. |
|
TXQUE |
Characters currently in the transmit buffer (READ-ONLY). |
|
XINPFLOW |
TRUE/FALSE Enable XON/XOFF input flow control.
When the DTE (computer) receive buffer is full, an XOFF character is sent
to the DCE (modem) to instruct it to halt transmission. When the
DCE is ready to resume transmission, an XON character is sent to the DCE.
Typically, XOFF is sent when the receive buffer has less than 1/16th remaining,
and XON is sent when the receive buffer drops to less than 1/16th of its
maximum size. Default = FALSE. |
|
XOUTFLOW |
TRUE/FALSE Enable XON/XOFF out flow control.
When enabled, the DCE (modem) sends an XOFF to the DTE (computer) to halt
data transmission to the DCE. When the DCE is ready to receive more
data, an XON character is sent. XOUTFLOW typically uses the same
1/16th rules as XINPFLOW. Default = FALSE. |
Attempting to set a READ-ONLY attribute will result
in a compile-time
("May not be altered").
The Number symbol (#) prefix is optional, but recommended
for the purposes of clarity.
