Model 2750 features Model 2750 is a 6 1⁄2-digit high-performance multimeter/data acquisition system. It can measure voltage (DC and AC), current (DC and AC), resistance (2- and 4-wire), temperature (thermocouple, thermistor, and 4-wire RTD), frequency and period, and test continuity. The Model 2750 has five slots that will accommodate Keithley Model 7700 series switching modules (Table 1-1). Each channel of a switching module that is closed or scanned is measured by the Model 2750. For scanning, each channel can have its own unique setup (i.e., function, range, digits, etc.). Additional features of Model 2750 include: Setup storage — Five instrument setups (three user, *RST defaults and factory defaults) can be saved and recalled. Offset compensated ohms — A two-measurement process for 4-wire ohms to cancel the effects of thermal EMFs. Available for the 1Ω, 10Ω, 100Ω, 1kΩ, and 10kΩ, ranges. Dry circuit ohms — Low voltage mode (20mV open-circuit clamping) for 4-wire ohms measurements. Available for the 1Ω, 10Ω, 100Ω, and 1kΩ ranges. Math — mX+b, percent, and reciprocal (1/X) calculations provide mathematical manipulation of readings. Relative — Null offsets or establish baseline values. Ratio and channel average — Ratio and average calculations for two switching module channels. Buffer — Store up to 110,000 readings in the internal buffer. Limits — Two sets of high and low reading limits to test devices. Digital I/O port — Five digital limit test output lines to control external circuitry. The digital trigger link and hardware interlock input can also be accessed at this port. Monitor — The Model 2750 can monitor a selected channel. A scan can be triggered to start when the Monitor detects a reached reading limit. Remote interface — Model 2750 can be controlled using the IEEE-488 interface (GPIB) or the RS-232 interface.