COM port Configuration Guide
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COM port Configuration Guide

Port Name of COM Port.
Baud Rate Transmission rate in bits per second.
Data Bits Number of data bits per byte.
Parity Choose None, Odd, Even, Mark or Space parity.
Stop Bits 1, 1.5 or 2 stop bits.
FIFO Bytes If you system have an 16550 UART that has a 16 byte receive buffer, then the FIFO setting should match the system Receive Buffer size (for Windows 95, start/settings/control panel/system/Device Manager/Port/Communication Ports/COMx/Port Settings/Advanced). A value of 8 seems adequate for most situations. A lower value will give better response time, but will use more CPU time. It is for end of receive frame detection. The system will assume that the end of frame is reached if does not receive any more data after that amount of character time.
BER The encoding Bit Error Ratio. Set to 0 to disable Reed Solomon Forward Error Correction (with Pseudo-random symbol interleaving).  The software will dynamically use RS(31,k) to RS(1023,k) depending on the BER and frame size. The second number is the measured BER of the transmitted data, the BER should be greater than this value. Each end must use the same BER.
Key 32 number for pseudo-random symbol interleaving. Press New to generate a new number. Each end must use the same key.
Compression ZIP software data compression.
None Do not use compression
Frame Compress at frame level only.
Streaming Streaming compression. Compression information are maintained across frame, this achieve much higher level of compression. The compression information are only reset on timeout.
Statistics Communication Statistics
Overrun Number of character overrun errors
Parity Number of parity errors
Framing Number of framing errors
Break Number of breaks
Rx Overflow Number of times the system receive buffer overflowed
Tx Overflow Number of times the system transmit buffer overflowed
Errors Corrected(Tx/Rx) Number of errors corrected on transmitted and received data.
BER(Tx/Rx) Bit Error Ratio of transmitted and received data.
Compression(Tx/Rx) Compression ratio of Transmit and Receive data
Bytes Total(Tx/Rx) Total number of bytes transmitted and received
Flow Control Input and Output flow control 
None No flow control
XON/XOFF Software Xon/Xoff flow control. 
RTS/CTS Raise RTS when input buffer is less than one-half full. Lower RTS when input buffer is more than three quarters full. Transmit only when CTS is high.
DTR/DSR Raise DTR when input buffer is less than one-half full. Lower DTR when input buffer is more than three quarters full. Transmit only when DSR is high.
DCD collision avoidance  For use in half duplex, multi-dropped system. Continuously wait for DCD to be low for at least the random quiescent time before each transmission. The quiescent time is a random time between min and max delay. 
CTS collision avoidance  For use in half duplex, multi-dropped system. Continuously wait for CTS to be low for at least the random quiescent time before each transmission.  The quiescent time is a random time between min and max delay. 
CTS Transmit only when CTS is high.
DSR Transmit only when DSR is high.
Direct Connection Direct connection to device.
Modem Use Modem.
Dial Telephone Number Telephone number to dial to make a connection.
Tone Dialling Use Tone dialling.
Pulse Dialling Use Pulse dialling.
Wait for incoming call Wait for incoming call.
Answer after n rings Answer incoming call after n rings
Init Sequence Modem initialisation sequence. Turn on Carrier Detect Signal when remote carrier signal is present, hang up when DTR is low and use Word responses. 
Half Duplex For use in situations where the Transmit and Receive lines are tied together. When enabled, the echoed transmitted characters are discarded.
Standby Not used
PTT Control Press To Talk Control. 
None RTS and DTR are on all the time
RTS Raise RTS only when sending data
DTR Raise DTR only when sending data
RTS and DTR Raise RTS and DTR only when sending data
Pre Transmission Delay (On Delay) Used with PTT Control, raise RTS or DTR and wait this time before transmitting data.
Post Transmission Delay (Off Delay) Used with PTT Control, after all data are transmitted, wait this time before dropping RTS or DTR.
Min Delay Used with DCD or CTS collision avoidance.
Max Delay Used with DCD or CTS collision avoidance.
 
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Last updated: 30 June 2016