HYDRA

Service Manual

The Microprocessor communicates to the Display Controller using a synchronous, three- wire communication interface controlled by hardware in the Microprocessor. Information is communicated to the Display Controller to display user interface menus and measurement data. Details of this communication are described in the Display Controller Theory of Operation in this section.

The Microprocess communicated to the Microcontroller on the A/D Converter PCA (via the Serial Communication circuit) using an asynchronous communication channel at 4800 baud. Communication to the Microcontroller (A3U9) originates at A1U1-54. Communication from the A/D’s Microcontroller to the Microprocessor appears at A1U1-

53.When there is no communication in progress between the Microprocessor and the Microcontroller, both of these signals are high.

The Microprocessor uses another asynchronous communication channel to communicate to external computing or modem equipment through the RS-232 interface. This interface is described in detail in the RS-232 Interface Theory of Operation in this section.

The third asynchronous communication channel in the Microprocessor is connected to the Option Interface (J1) but is not used in the instrument at this time.

The interrupt controller in the Microprocessor prioritizes interrupts received from hardware devices both internal and external to the Microprocessor. Table 2A-1 lists interrupt sources from highest to lowest priority.

Table 2A-1. Microprocessor Interrupt Sources (2635A)

Pin

A1U1-95

A1U1-96

A1U1-121

A1U1-119

A1U1-97

Signal Name

XTINT*

CINT*

KINT*

MCINT*

OINT*

Description

External Trigger Interrupt (Highest Priority)

Real-Time Clock Interrupt; once per second

Keyboard Interrupt; interrupts on each debounced change of keyboard conditions.

RS-232 Interface Interrupt; internal to the Microprocessor.

A/D Communication Interrupt; internal to the Microprocessor.

Timer Interrupt every 53.333 milliseconds; internal to the Microprocessor.

Memory Card Interface Interrupt; interrupts when a memory card is inserted, removed, powered up or powered down.

Totalizer Interrupt; internal to the Microprocessor. Interrupts on totalizer overflow from a count of 65535 to 0.

Option Interface Interrupt; not currently used in this product.

The Microprocessor also has several internal DMA (Direct Memory Access) controllers that are used by the serial communication channels. Each serial communication channel has a DMA channel that handles character reception and another that handles character transmission. The use of these DMA controllers is transparent to the external operation of the Microprocessor, but it is important to understand that communication is handled at hardware speeds without the need for an interrupt for each character being transferred.

A watchdog timer internal to the Microprocessor is programmed to have a 10-second timeout interval. If the code executed by the Microprocessor fails to reinitialize the watchdog timer every 10 seconds or less, then A1U1-117 (POR*) is driven low for 16 cycles of SCLK (approximately 1.3 microseconds). This results in a complete hardware reset of the instrument, which restarts operation.

2A-12

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Fluke 2625A service manual Microprocessor Interrupt Sources 2635A Pin, Signal Name
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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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