Carrol Touch TouchSystems CarrollTouch Prog, Programmer'S Manual

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Appendix A - Smart-Frame Protocol Command Reference CARROLL TOUCH
A-28 Touch System Programmer’s Guide
Hardware_Flow_Control_On (41H) (A)
Command Description
When the host sends the Hardware_Flow_Control_On (41H)
command, the touch system uses hardware handshaking to regulate
serial communications with the host. Carroll Touch touch systems use
one of two hardware flow control methods, depending on the type of
touch system.
Modular RS-232 Controller
The Clear To Send (
CTS
) signal is used to regulate data transmission
from the host to the touch system. The touch system controls the state
of the
CTS
signal and asserts
CTS
by applying a positive voltage and
deasserts
CTS
by applying a negative voltage. If
CTS
is asserted, the
touch system is ready to receive commands. If
CTS
is deasserted, the
touch system is processing a command or performing some other
activity, and is not ready to receive commands.
The Data Terminal Ready (
DTR
) signal is used to regulate data
transmission from the touch system to the host. The host controls the
state of the
DTR
signal and should assert
DTR
by applying a positive
voltage and deassert
DTR
by applying a negative voltage. If the host
asserts
DTR,
the touch system transmits Smart-Frame Protocol reports
to the host. If the host deasserts
DTR
, no reports are transmitted from
the touch system to the host.
Smart-Frame Type Touch Systems
The hardware flow control method is the same as for the modular
RS-232 controller with one exception. If the Request To Send (
RTS
)
signal is deasserted, the Clear To Send (
CTS
) signal is always
deasserted, regardless of whether or not the touch system is ready to
receive commands. If
RTS
is asserted, the
CTS
signal reflects the ready
state of the touch system. If
CTS
is asserted, the touch system is ready
to receive commands; if not, the touch system is not ready.
See Also
Hardware_Flow_Control_Off (42H)