Serial Port Monitoring Control - ActiveX Component Library for RS232 Data Monitoring, API for Software Developers
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MODEMSTATUS Enumeration

Modem status flags. These masks are used to access the modem status register. Whenever one of the first four bits in the modem status register changes state a modem status interrupt is generated.

SymbolValueDescription
HHD_SERIAL_MSR_DCTS0x00000001This bit is the delta clear to send. It is used to indicate that the clear to send bit (in this register) has changed since this register was last read by the CPU.
HHD_SERIAL_MSR_DDSR0x00000002This bit is the delta data set ready. It is used to indicate that the data set ready bit (in this register) has changed since this register was last read by the CPU.
HHD_SERIAL_MSR_TERI0x00000004This is the trailing edge ring indicator. It is used to indicate that the ring indicator input has changed from a low to high state.
HHD_SERIAL_MSR_DDCD0x00000008This bit is the delta data carrier detect. It is used to indicate that the data carrier bit (in this register) has changed since this register was last read by the CPU.
HHD_SERIAL_MSR_CTS0x00000010This bit contains the (complemented) state of the clear to send (CTS) line.
HHD_SERIAL_MSR_DSR0x00000020This bit contains the (complemented) state of the data set ready (DSR) line.
HHD_SERIAL_MSR_RI0x00000040This bit contains the (complemented) state of the ring indicator (RI) line.
HHD_SERIAL_MSR_DCD0x00000080This bit contains the (complemented) state of the data carrier detect (DCD) line.