On-line data acquisition system for Perkin-Elmer 240 carbon,hydrogen, and nitrogen analyzer

The Perkin-Elmer 240 CH and N analyzer was adapted for on-line data acquisition with a remote computer. Sample weights from a Cahn electrobalance are directly entered into the computer via a power supply and interrupt system. The outputs from the three thermal conductivity detectors are monitored for 10 sec and signal averaged by the computer. The computer takes all data necessary for the calculation of percent CH and N and prints out a final report on a Silent 700 remote terminal. The report is suitable for direct transmission to the sample submitter. Duplicate reports are printed for permanent analytical records. The precision of results obtained with on-line data acquisition compare favorably to results calculated manually, and provides a 38% improvement in efficiency. The on-line systems employ a PDP-15/76 computer, which is available for other tasks. This provides an additional cost savings compared to the alternate approach of purchasing a small dedicated computer.