COMx driver special options reference

Special Options (in the Ports form) are space separated and start with the dash character (-) immediately followed by the option characters. Only a small percentage of users will need to use the following options:

• cATS0=1: Send the string 'ATS0=1<CR>' on startup to allow the modem to detect the baud rate the port is running at. Abandon transmit if DCD is low. Wait for incoming call to raise DCD.

• d: Data will be transmitted only when DSR is high
• di: Received data is ignored when DSR is low.
• dMS: When transmitting a message the driver will wait up to 2000 ms for DSR to go high, then wait another MS milliseconds before transmitting.
• -e: Provides access to the output signal lines. The format is "~EIAWXYZ" where WXYZ represents one of the following options:

S Simulate XOFF received

S Simulate XON received

RT Set RTS high

RT Set RTS low

D Set DTR high

D Set DTR low

B Set the device break line

B Clear the device break line

Example: "~EIADTR1" sets DTR high

• -h: Data will be transmitted only when CTS is high.
• -hMS: When transmitting a message the driver will wait up to 2000 ms for CTS to go high, then wait another MS milliseconds before transmitting.
• -i: The string sent whenever the port is initialized. The tilde (~) and '\M' characters represent special instructions:

• ~: Delay for 500 milliseconds
• \M: Send carriage return

Examples:

~Fred: Wait 500 milliseconds and then send 'Fred'

Fred\MMary: Send 'Fred', a carriage return, and then 'Mary'

Note: This option is not available for dialable devices (i.e. when the port number is -1).

• -nt: With some serial interfaces, line interruptions can cause the COMx read thread to shutdown. If this happens, the driver does not recover after the interruption. However, with the -nt (no terminate) option set, the thread is not shutdown, allowing the system to recover when the interruption is rectified.
• -nts: If errors occur when the COMx driver is starting up, it will not terminate, but will continue attempts to open the COMx port.
• -r: Driver will raise DTR only when transmitting.
• -ri: DTR is raised when there is enough room in the input buffer to receive incoming characters and drop DTR when there is not enough room in the input buffer.
• -rPRE,POST: When transmitting a message the driver will raise DTR for PRE milliseconds, transmit message, wait for POST milliseconds then drop DTR.
• -sc: Activates software flow control using XON and XOFF

XonLim: A number in bytes. This represents the level reached in the input buffer before the XON character is sent (30 bytes)

. XoffLim: The maximum number of bytes accepted in the input buffer before the XOFF character is sent. This is calculated by subtracting (in bytes) 100 from the size of the input buffer

• -t: Driver will raise RTS only when transmitting.
• -ti: RTS is raised when there is enough room in the input buffer to receive incoming characters and drop RTS when there is not enough room in the input buffer.
• -to: RTS is raised only when there are characters to transmit.
• -tPRE,POST: When transmitting a message the driver will raise RTS for PRE milliseconds, transmit message, wait for POST milliseconds then drop RTS..

See Also