Theory of Operation (2635A) 2A

Detailed Circuit Description

2A-14.Channel Selection Circuitry

This circuitry consists of a set of relays and relay-control drivers. The relays form a tree that routes the input channels to the measurement circuitry. Two of the relays are also used to switch between 2-wire and 4-wire operation.

2A-15.Open Thermocouple Check Circuitry

Under control of the Inguard Microcontroller, the open thermocouple check circuit applies a small ac signal to a thermocouple input before each measurement. If an excessive resistance is encountered, an open thermocouple input condition is reported.

2A-16. Input Connector Assembly

The following paragraphs briefly describe the major sections of the Input Connector PCA, which is used for connecting most of the analog inputs to the instrument.

2A-17.20 Channel Terminals

Twenty HI and LO terminal blocks are provided in two rows, one for channels 1 through 10 and one for channels 11 through 20. The terminals can accommodate a wide range of wire sizes. The two rows of terminal blocks are maintained very close to the same temperature for accurate thermocouple measurements.

2A-18.Reference Junction Temperature

A semiconductor junction is used to sense the temperature of the thermocouple input terminals. The resulting dc output voltage is proportional to the block temperature and is sent to the A/D Converter PCA for measurement.

2A-19. Display PCA

The Display Assembly controller communicates with the main Microprocessor over a three-wire communication channel. Commands from the Microprocessor inform the Display Controller how to modify its internal display memory. The Display Controller then drives the grid and anode signals to illuminate the required segments on the Display. The A2 Display Assembly requires power supply voltages from the Power Supply, a reset signal from the Reset Circuit, and a clock signal from the Digital Kernel.

2A-20. Memory Card Interface PCA

The Memory Card Interface PCA is used to access the memory on an industry standard memory card installed through the slot in the front panel of the instrument. This assembly allows management of the memory card power, adapts timing of accesses by the Digital Kernel to the memory card, and provides visible indicators for low battery voltage and memory card busy status.

2A-21. Detailed Circuit Description

2A-22. Main PCA

>The following paragraphs describe the operation of the circuits on the Main PCA. The schematic for this pca is located in Section 8.

2A-7

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Fluke 2625A 2A-21. Detailed Circuit Description, 2A-16. Input Connector Assembly, 2A-19. Display PCA, 2A-22. Main PCA
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2635A, 2625A specifications

The Fluke 2625A is a sophisticated data logger designed for a wide range of industrial and laboratory applications. This versatile instrument excels in capturing and monitoring temperature and voltage measurements with precision and reliability. One of its standout features is its ability to record data from various sensors, making it ideal for environments where comprehensive data acquisition is critical.

Equipped with a large LCD display, the Fluke 2625A provides clear and user-friendly access to real-time measurement data. Its graphical interface allows users to visualize trends and monitor readings easily, which significantly enhances usability. The device supports a variety of input types and can connect to thermocouples, RTDs, and other sensors, offering great flexibility for various measurement tasks.

The Fluke 2625A employs advanced measurement technologies that ensure accuracy in data logging. With a high sampling rate, it captures fast-changing signals while maintaining data integrity. The device features a built-in memory that allows for extensive logging, accommodating long-term monitoring tasks without requiring constant oversight. Users can set it to log data at specified intervals, offering customizable solutions for different monitoring needs.

Another significant characteristic of the Fluke 2625A is its robust communication capabilities. The device supports USB and RS-232 interfaces for easy connectivity with computers and other devices, making data transfer and analysis seamless. This feature is especially beneficial for users who need to compile or analyze large sets of data quickly.

Furthermore, the Fluke 2625A is designed with durability in mind. Its rugged construction makes it suitable for challenging environments, including those with high levels of vibration, dust, or moisture. This reliability ensures that the device can withstand the rigors of fieldwork while still delivering accurate measurements.

In summary, the Fluke 2625A is a powerful data logger that combines versatility, accuracy, and reliability. Its user-friendly interface, advanced measurement technologies, and robust design make it an essential tool for professionals in various industries, from manufacturing and HVAC to research and development. Whether monitoring temperature changes in a laboratory or assessing voltage levels in an industrial setting, the Fluke 2625A stands out as a trusted solution for effective data logging and analysis.
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