USRobotics V.34 user manual Software Control &In

COURIER HIGH SPEED MODEMS

&H3 Use both hardware and software flow control. If you are unsure about what your equipment supports, select this option. But keep the warning, above, in mind about software flow control.

Received Data Flow Control

Separate commands, &Rn (hardware) and &In (software), con- trol the flow of Received Data passed by the Courier to your computer or terminal.

Your software and machine must support whichever type you select, although we recommend hardware flow control, if possible.

Hardware Control(&Rn)

&R0	Delay Clear to Send Response after Request to Send
	signal (RTS/CTS delay). The delay is required by some
	synchronous mainframes and does not apply to
	asynchronous calls.
&R1	The modem ignores RTS. This setting is required if your
	computer or terminal or software does not support RTS.
&R2	Hardware flow control of received data enabled.
	Default. The modem sends data to the computer or
	terminal only on receipt of the RTS signal.

Software Control (&In)

WARNING: In ordinary operation, the only characters the modem recognizes during a call are the three pluses (+++) of the escape code. But when software flow control is enabled, the modem also looks for <Ctrl>-S or <Ctrl>-Q characters. If these characters occur in a file or as part of a protocol, the modem reads them as XON/XOFF characters and acts on them. In some cases, the modem drops them from the data stream.

&I0 Disables XON/XOFF flow control of received data. Default. Recommended for non-ARQ (Normal mode) calls, but see &I5. The I0 option provides transparency for all characters except the escape code sequence (+++), because at this setting the modem does not look for control characters.

Data Mode Operations 4-27