Modemulator User Guide
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Appendix F: Flow Control
1. Hardware Flow Control
H/W Transmit Flow Control
When the Modemulator's incoming transmit data buffer is getting full, it will de-assert the Clear to
Send (CTS) signal on the RS-232 interface, which commands the local DTE to stop sending
transmit data to the Modemulator. When sufficient space becomes available, CTS will be re-
asserted, enabling data flow.
H/W Receive Flow Control
If set to &R2, the Modemulator will obey the incoming Request to Send (RTS) signal, sending or
stopping receive data to the local DTE.
2. Software Flow Control
S/W Transmit Flow Control
When the Modemulator's incoming transmit data buffer is getting full, it will send the
programmable Xoff character to the local DTE, which commands the DTE to stop sending transmit
data to the Modemulator. When sufficient space becomes available, the programmable Xon
character will be sent, enabling data flow.
S/W Receive Flow Control
If set to &I1 or &I2, the Modemulator will obey the incoming Xon/Xoff flow control characters,
sending or stopping receive data to the local DTE. &I1 will pass Xon/Xoff through to the remote
Modemulator, while &I2 will not.
S/W flow control should not be used for binary file transfers, since Xon and Xoff characters in the
data could be falsely interpreted as flow control.
