When the Manual Flow Control setting selected, the Flow Control is managed by the relevant ClearSCADA driver. When the driver is ready to send a message, it instructs the operating system to raise the RTS signal. The RTS signal informs the 'receiving' communications equipment that data is about to be sent.
After instructing the operating system to raise an RTS connection, the ClearSCADA driver waits for the Pre-message RTS Delay time. The delay allows the 'receiving' communications equipment time to prepare itself to receive the actual data.
On an advanced driver channel, if the Abort Pre-message Delay if CTS Raised setting is enabled, ClearSCADA will abort the Pre-message RTS Delay timer when it detects that CTS has been asserted. The data will then be transmitted.
Following sending the data to the operating system, an advanced ClearSCADA driver waits for the Post-message RTS Delay time before instructing the operating system to lower the RTS signal. This delay allows the 'receiving' equipment time to finish processing the data. If the device is just one part of a chain of devices, the Post-message RTS Delay time may be the delay required for the device to finish forwarding the data to a downstream device.
When the Post-message RTS Delay time has expired, the ClearSCADA driver instructs the operating system to lower the RTS signal. (On simple driver channels, the driver instructs the operating system to lower the RTS signal when its transmission buffer is empty.)
The Abort Pre-message Delay if CTS Raised and Post-message RTS Delay properties only apply to Serial connections on advanced driver channels. They do not apply to Remote Serial connections.