The Keithley 740 System Scanning Thermometer delivers precision temperature measurement and data acquisition across an extended range of -200°C to +1820°C. This instrument measures thermocouple and millivolt signals from seven thermocouple types (J, K, T, E, R, S, B), with expandable multi-channel architecture supporting up to 81 channels via optional scanner cards. The 740 executes high-speed scanning at greater than 20 channels/second (filter disabled) or greater than 5 channels/second (filter enabled), with bench reading rates of 8 readings/second or 4 readings/second respectively.
Technical Specifications
• Temperature range: -200°C to +1820°C
• Supported thermocouples: J, K, T, E, R, S, B
• Channel capacity: 1 internal; expandable to 9 channels (7057A card) or 81 channels (multiple cards)
• Scanning rate: >20 ch/s (unfiltered), >5 ch/s (filtered)
• Bench reading rate: 8 readings/s (unfiltered), 4 readings/s (filtered)
• Data memory: 100 locations (single channel), 90 locations (multi-channel), 81 locations (configuration)
• Battery backup: Minimum one week
• Logging interval: 12 selectable rates from 50 ms to 1 hour, or triggered
• Input resistance (mV mode): >1 GΩ
• Maximum thermocouple loop resistance: 1 kΩ
• Maximum input: 250 V rms, 350 V peak (1 minute duration)
• Maximum common mode voltage: 200 V peak to earth
• Power requirements: 105–125 V or 210–250 V AC (switch selectable), 20 VA, 50/60 Hz
• Warmup time: 1 hour to rated accuracy
• Internal clock: Hour/minute/second display; <1 minute/month error (typical)
• Temperature scale: °C or °F selectable
• Calibration: Digital; no internal adjustments required
• Open thermocouple detection: Supported
– Key Features
• IEEE 488 GPIB interface with full command set (SH1, AH1, T6, TE0, L4, LEO, SR1, RL1, PP0, DC1, DT1, E1, C28)
• TTL-compatible BNC connectors for external trigger, serial in/out
• 8-digit alphanumeric LED display with decimal point and polarity indication
• Status indicators: Function, Filter, Channel, Location, Overflow, Open Thermocouple, IEEE bus
• Compact footprint: 127 mm H × 216 mm W × 359 mm D
– Compatibility & Integration
The 740 integrates with IEEE 488 systems via multiline (DCL, LLO, SDC, GET, GTL, UNT, UNL, SPE, SPD, MLA, MTA) and uniline (IFC, REN, EOI, SRQ, ATN) commands. Smart Print mode enables operation with talk and listen-only devices.
