The 2686A comes with a removable PC Card (PCMCIA) for stand-alone storage operation. This socket accepts ATA memory cards up to 2 GB in size. Each 268XA device can hold from 1 to 6 analog modules. These modules are the Precision Analog module (PAI), Fast Analog module (FAI), and the Digital IO/Relay and Totalizer module (DIO). These modules are all isolated from one another. You can add the DIO module to the device in slot 6 only. The analog modules measure dc volts, ac volts, ohms, temperature, frequency, and dc current. Temperature measurements use thermocouples, thermistors or resistance temperature detectors (RTDs). The devices also have extensive computed math capability. Besides using data collected from the analog modules and digital totalizer, time can also be used in computed channel calculations. The system scans 20 to 120 analog channels and calculates the values for up to 60 computed channels. Interval timers, alarm conditions, and/or an external signal input can trigger scans. The Fluke DAQ software configures and controls up to 99 268XA devices via an Ethernet connection. The software provides the means to view scan data and log it into files. The analog modules that may be used with the 268XA are the FAI module and the PAI module. The PAI modules emphasize precision with 5 ½ digits of resolution, .02% accuracy, and can withstand up to 150 V common mode voltage (300 V on channels 1 and 11). The FAI modules emphasize increased measurement speed with 4 ½ digits of resolution, 0.04% accuracy, and can withstand up to 50 V common mode voltage. Device specifications are provided later in this chapter.