22 Chapter 2: TempScan/1100 & MultiScan/1200 TempScan / MultiScan User's Manual
The following text describes the various pin connector signals:
• Transmit Data Negative (TxD-): This output 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 particular port. This signal is low true.
• Transmit Data Positive (TxD+): This output pin transmits serial data to an RS-422 device only.
The pin functions identically to TxD- except that its polarity is inverted. This signal is high true.
• Receive Data Negative (RxD-): This input 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 configuration of the particular port. This signal is low true.
• Receive Data Positive (RxD+): This input pin accepts serial data sent by an RS-422 device only.
It functions identically to RxD- except that its polarity is inverted. This signal is high true.
• Request To Send Positive (RTS+): This output pin is used as a hardware handshake line to prevent
an RS-232 or RS-422 device from transmitting serial data to the TempScan/1100 or
MultiScan/1200 unit when it is not able to accept it. When automatic RTS/CTS handshaking is
selected, the unit 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, the unit unasserts
(low) the RTS+ signal.
• Request To Send Negative (RTS-): This output pin is used as a hardware handshake line with an
RS-422 device only. The pin functions identically to RTS+ except that its polarity is inverted.
This signal is low true.
• Clear To Send Positive (CTS+): This input pin is used as a hardware handshake line to prevent the
TempScan/1100 or MultiScan/1200 unit 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, the unit will not
Transmit Data (TxD+) out while the CTS+ signal is un-asserted (low). When XON/XOFF or no
handshaking is selected, the CTS+ line is ignored.
• Clear To Send Negative (CTS-): This input pin is used as a hardware handshake line with an RS-
422 device only. It functions identically to CTS+ except that its polarity is inverted. This signal is
low true.
• Ground (GND): This signal sets the ground reference point for the other RS-232/RS-422 input
and output signals.
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