This poster describes the development of an ESI guided-ion-beam tandem mass spectrometer, along with instrument control and data acquisition. ESI generated ions are introduced into the instrument, and mass-selected by a reactant mass filter. Mass-selected ions are guided into an octopole ion guide, and react with neutral reactant in a scattering cell surrounding the octopole. Product ions and the remaining reactant ions are collected by the octopole ion guide, and extracted into the product mass filter for analysis. Using this instrument reaction cross section could be measured as a function of collision energy. A LabVIEW Virtual Instrument (VI) was developed for instrument control and data acquisition, with the utilization of a NI PCI-6229 multifunction analog and digital DAQ board installed in an Intel dual core PC. We use the 80 MHz timer/counters on the DAQ board for gating and event counting, and as the master clock to synchronize various outputs. One digital output is used to control the duty cycle of scattering cell on/off, and one analog output is used to set the collision energy for ion-molecule reactions. Various parameters, including voltages on electrical lens and ion detectors, are controlled by the DAQ board and could be manipulated through the VI front panel. The quadrupole mass filters are currently controlled by an Extrel Merlin controller, and an interface is being developed to integrate this controller to the LabVIEW VI.