Serial Port Mode Editor

Introduction

The Serial Port Mode String is a text string that configures how a serial port operates. The string configures the speed of the communications link, the data format and whether there is any flow control enabled.

The Serial Port Mode Editor is a dialog to help you configure serial port mode strings:

Serial Port Mode Editor Dialog

The Serial Port Mode Editor is accessed by clicking the Browse button Browse button in the Properties Window.

Serial Port Properties

ParameterDescription
Baud RateThe speed of the communication channel in bits per second.
Data BitsThe number of data bits in each character
Parity Whether a parity check bit is added to the data, and if so what type of parity check bit. The options are:
  • None = No parity bit is added to the data.
  • Even = The parity bit is set to space (0) if the total number of data bits in the mark (1) state is even.
  • Odd = The parity bit is set to space (0) if the total number of data bits in the mark (1) state is odd.
  • Mark = The parity bit is set to mark (1).
  • Space = The parity bit is set to space (0).
Stop BitsThe number of stop bits at the end of each character
Xon/Xoff Whether the xon/xoff software flow control is enabled. When enabled:
  • Fernhill SCADA will stop transmitting when an XOFF character (ASCII DC3) is received.
  • Fernhill SCADA will resume transmitting when an XON character (ASCII DC1) is received.
Xon/Xoff software flow control is generally not compatible with binary communication protocols, for example Modbus RTU.
RTS Control How Fernhill SCADA manages the Request To Send (RTS) handshake signal. The options are:
  • Always On = RTS signal is always on.
  • Always Off = RTS signal is always off.
  • Handshake = RTS signal is on when the input buffer is less than 50% full. RTS signal is off when the input buffer is more than 75% full.
  • Toggle = RTS signal is on when there are bytes available for transmission.
CTS Whether the Clear To Send (CTS) signal is monitored for output flow control. The options are:
  • Ignore = Data is sent regardless of the state of the Clear To Send (CTS) signal.
  • Suspend TX = Data is only sent if the Clear To Send (CTS) signal is On.
DTR Control How Fernhill SCADA manages the Data Terminal Ready (DTR) handshake signal. The options are:
  • Always Off = DTR signal is off.
  • Always On = DTR signal is on.
  • Handshake = DTR handshaking is enabled.
DSR Whether the Data Set Ready (DSR) signal is monitored for output flow control. The options are:
  • Ignore = Data is sent regardless of the state of the Data Set Ready (DSR) signal.
  • Suspend TX = Data is only sent if the Data Set Ready (DSR) signal is On.

Further Information

Serial Communications

For background information on serial communications.

Serial Port Mode String

For detailed information on the format of the serial mode string.

Glossary

For the meaning of terms used in Fernhill SCADA.