LabComm collects data from an analyser by connecting to the analyser, interpreting the data stream and storing the data. Analysers use serial, ethernet or USB ports to send and receive data.

Serial ports are also known as RS232 ports. RS232 ports can have different active pins or connections in the port and this may require that a cable with a specific pin configuration is made. LabComm provides the correct serial cables as part of the process of interfacing to the analyser

There are many possible cable configurations. The “standard” pin outs are shown below.

9-Pin Connector

RXD pin 2   ----------------------------------------      TXD     pin   3 
TXD pin 3   ----------------------------------------       RXD    pin   2 
DTR pin 4  ------------------------------------------     DSR    pin   6 
GND pin 5 ----------------------------------------       GND     pin   5
DCD pin 1  ----------------------------------------       DTR     pin   4 
RTS  pin 7   ----------------------------------------     CTS     pin    8 
CTS  pin 8 ------------------------------------------     RTS     pin   7

It is simpler to view the pin-outs from a drawing in a graphical format:

  • Simple null modem without handshaking

 This cable is the simplest to understand as there are only three lines in use - the signal ground the transmit and receive data lines. One wire transmits the data, a different wire sends the data and one wire acts as the signal ground

 The top diagram shows the 9 pin connections and the lower one shows the 25 pin ones.


Serial null modem

  • Null modem with loop back handshaking

This is the nearest to a “standard” and is used by the majority of analysers.


Serial null modem full

  • Null modem with partial handshaking

Serial null modem partial

  • Null modem with full handshaking

Serial loop backup

The original pin layout for RS232 was developed for a 25 pin D sub connector. With this pin-out configuration provisions were made for a secondary communication channel. In practice, only one communication channel with accompanying handshaking is present. For that reason, as well as the move towards miniaturisation the smaller 9 pin version is much more common.

Note: The protective ground is assigned to a pin at the large connector, in DB9 version protective ground connector to the enclosure.
Serial cables for the analysers to be interfaced are supplied by LabComm.