Abstract: A method for monitoring the concentration of at least one volatile or semi-volatile compound contained in at least one air stream carrying at least one volatile or semi-volatile compound and apparatus for performing the method, which includes the steps of calibrating at least one gas chromatograph using at least three different calibration gases, obtaining a sample of the at least one air stream containing the at least one compound, providing the sample of the at least one air stream to the at least one gas chromatograph under control of a digital data processor to analyze the sample of the at least one air stream to determine the concentration of the at least one compound in the sample and controlling the operations using the digital data processor.

Abstract: A network bridge between a DEC Ethernet network using LAT protocol and an Allen-Bradley Data Highway/Data Highway Plus (DH/DH+) network eliminates the need to use a DEC terminal server and Allen-Bradley KE/KF2 interface with their low data rates. A terminal server emulator is electrically connected to the DEC Ethernet network for stripping the LAT protocol from the DEC Ethernet network and provide DF1 formatted data. A converter module is electrically connected between the terminal server emulator and the DH/DH+ network for converting the DF1 data into DH/DH+ protocol data and for transmitting this data to the DH/DH+ network. The converter also converts data using DH/DH+ protocol which is received from the DH/DH+ network into DF1 data and transmits this data to the terminal server emulating means. The terminal server emulating means then places the DF1 formatted data into LAT packets and transmits the LAT packets to the Ethernet network.