Yamaha RCX240, User Manual

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Chapter 8 RS-232C INTERFACE Chapter 8 RS-232C INTERFACE
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3.3 Communication flow control
Software flow control (XON/XOFF) and hardware flow control (RTS/CTS) methods can be selected
by specifying the communication parameters.
3.3.1 Flow control during transmit
XON/XOFF and CTS indicate whether the other party can receive data.
Flow Control Yes No
XON/XOFF
Temporarily stops transmission
when XOFF is sent from the other
party.
Resumes transmission when XON
is sent.
XON (11H) and XOFF (13H) do not
affect transmission even when they
are received.
RTS/CTS
Stops transmission while CTS is
OFF. Stops transmission while CTS is
OFF.
n
NOTE
1) Transmission stops when transmission is disabled in either of XON/XOFF or RTS/CTS
flow control.
2) CTS must be on during transmission regardless of flow setting. When RTS/CTS is set
to "No", the CTS should always be set on. However, if CTS is connected to RTS of
the other party, CTS may not always be on causing the transmission to halt,
depending on the other party specifications.
3.3.2 Flow control during receive
To prevent overflow when receiving data, XOFF and RST are used to notify the other party that this
end is busy.
Flow Control Yes No
XON/XOFF
Transmits XOFF when available
space in receive buffer falls below
a certain capacity.
Transmits XON when receive buffer
is empty.
XON and XOFF are not transmitted.
XON and XOFF are ignored if
received.
RTS/CTS
Turns RTS off when available
space in receive buffer falls below
a certain capacity.
Turns RTS on when receive buffer
is empty.
RTS is always on.
n
NOTE
The flow controls the functions separately. For instance, when all flow controls are
set to "Yes" and the receive buffer capacity is low, an XOFF is transmitted, and RTS is
turned off. Later, when the receive buffer capacity is restored, an XON is
transmitted, and RTS is turned on.
3. Communication specifications