Menu Tools > Project Settings... | Flow Control
Used to specify additional hardware or software flow control settings for serial communications in Docklight Send/Receive Mode.
No hardware or software flow control mechanism is used. RTS and DTR are enabled when the COM port is opened.
Use this mode to control the RTS and DTR signals manually and display the current state of the CTS, DSR, DCD and RI lines. If flow control is set to "Manual", an additional status element is displayed in the Docklight main window. You may toggle the RTS and DTR lines by double clicking on the corresponding indicator.
NOTE: Flow control signals are not treated as communication data and will not be displayed in the communication window or logged to a file.
Hardware Handshaking, Software Handshaking
Support for RTS/CTS hardware flow control and XON/XOFF software flow control. These are expert settings rarely required for recent communication applications.
Some RS232-to-RS485 converters require manual RTS control, i.e. the RS232 device (PC) tells the converter when it should enable its RS485 driver for transmission. If you choose "RS485 Transceiver Control", the COM port sets RTS to High before transmitting the first character of a Send Sequence, and resets it to Low after the last character has been transmitted.
NOTE: Many USB-to-Serial converters or virtual COM port drivers do not implement the Windows RTS_CONTROL_TOGGLE mode properly. If you experience problems with RS485 Transceiver Control, try using a PC with an on-board COM interface or a standard PCI COM card.