Hardware 3-9
Serial Port Pin Connector Signals for RS-232/422 Applications
RxD- (Receive Data Negative) Input: This pin accepts serial data sent by an RS-232 or RS-422 device. The serial data
received is expected to match the word length, baud rate, stop bits, and parity configuratio n of the particular port. The signal is
low true.
RxD+ (Receive Data Positive) Input: This pin accepts serial data sent by an RS-422 device only. The signal is high true.
TxD- (Transmit Data Negative) Output: This pin transmits serial data to an RS-232 or RS-422 device. The serial data
received is sent with the word length, baud rate, stop bits, and parity configured for the particu lar port. The signal is low true.
TxD+ (Transmit Data Positive) Output: This pin transmits serial data to an RS-422 device only. The signal is high true.
CTS- (Clear To Send Negative) Input: CTS- input is used as a hardware handshake line to prevent ChartScan from
transmitting serial data to an RS-232 or RS-422 device when it is not able to accept it. When RTS/CTS handshaking is selected,
ChartScan will not transmit data out TxD- while this signal is un-asserted (low). If XON/XOFF or no handshaking is selected,
the CTS- line is ignored when transmitting data. The signal is low true.
CTS+ (Clear To Send Positive) Input: CTS+ input is used as a hardware handshake line to prevent ChartScan from
transmitting serial data to an RS-422 device when it is not able to accept it. The signal is high true.
RTS- (Request To Send Negative) Output: RTS- output is used as a hardware handshake line to prevent an RS-232 or RS-422
device from transmitting serial data to ChartScan when it is not able to accept it. When automatic RTS/CTS handshaking is
selected, ChartScan will assert (high) the RTS- signal when greater than 4096 memory locations are available in its internal
buffers. If available memory drops below 4096 bytes, ChartScan unasserts (low) the RTS- signal. The signal is low true.
RTS+ (Request To Send Positive) Output: RTS+ output is used as a hardware handshake line for an RS-422 device. The
signal is high true.
GND (Ground): This signal sets the ground reference point for the other RS-232/RS-422 input and output signals.