![Fluke NetDAQ 2640A Скачать руководство пользователя страница 57](http://html1.mh-extra.com/html/fluke/netdaq-2640a/netdaq-2640a_service-manual_2310217057.webp)
Theory of Operation
Detailed Circuit Description
2
2-15
One sixteen-bit timer in the Microprocessor is used to keep track of the time to the
nearest millisecond. The timer counter runs off the 15.36 MHz clock at a rate of 1/64th
millisecond. The CINT* signal from the Real Time Clock chip (A1U11) causes the timer
counter to be sampled every 1/64th of a second. The CINT* signal also interrupts the
Microprocessor to provide a timing reference for the software. The combination of the
counter and the interrupt are used by the software to keep track of the time to the nearest
millisecond, referenced to the Real Time Clock Chip.
A second sixteen-bit timer in the Microprocessor is used for an interval timer. It is also
clocked at a rate of 1/64th millisecond. This timer interrupts the Microprocessor at a rate
determined by the application.
The Microprocessor has two parallel ports. Many of the parallel port pins are either used
as software controlled signals or as inputs or outputs of timers and serial communication
channels. Port A has 16 bits and Port B has 12 bits.
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 chapter.
The Microprocessor communicates to the A/D Microprocessor on the A/D Converter
PCA (via the Serial Communication circuit) using an asynchronous communication
channel at 120,000 baud. Communication to the A/D Microprocessor (A3U5) originates
at A1U1-80. Communication from the A/D’s Microprocessor to the Microprocessor
appears at A1U1-52. When there is no communication in progress between the
Microprocessor and the A/D Microprocessor, 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 chapter.
The third asynchronous communication channel in the Microprocessor is connected to
the Debug Interface (P3). This connector is not installed in production assemblies.
The interrupt controller in the Microprocessor prioritizes interrupts received from
hardware devices both internal and external to the Microprocessor. Table 2-1 lists
interrupt sources from highest to lowest priority.
Содержание NetDAQ 2640A
Страница 14: ...NetDAQ Service Manual x...
Страница 46: ...NetDAQ Service Manual 2 4...
Страница 106: ...NetDAQ Service Manual 2 64...
Страница 108: ...NetDAQ Service Manual 3 2...
Страница 164: ...NetDAQ Service Manual 4 42...
Страница 206: ...NetDAQ Service Manual 6 2...
Страница 218: ...NetDAQ Service Manual 6 14 2645A 1601 Figure 6 2 A1 Main PCA Assembly...
Страница 220: ...NetDAQ Service Manual 6 16 2620A 1601 Figure 6 3 A2 Display PCA Assembly...
Страница 225: ...List of Replaceable Parts Parts Lists 6 6 21 2640A 1603 Figure 6 4 2640A A3 A D Converter PCA Assembly...
Страница 230: ...NetDAQ Service Manual 6 26 2645A 1603 Figure 6 5 2645A A3 A D Converter PCA Assembly...
Страница 234: ...NetDAQ Service Manual 7 2...
Страница 242: ...2640A 2645A Service Manual 7 10 Figure 7 2 A2 Display PCA Assembly 2620A 1602...
Страница 243: ...Schematic Diagrams 7 7 11 Figure 7 2 A2 Display PCA Assembly cont 2620A 1002...
Страница 244: ...2640A 2645A Service Manual 7 12 2640A 1603 Figure 7 3 2640A A3 A D Converter PCA Assembly 2640A 1603...
Страница 251: ...Schematic Diagrams 7 7 19 2645A 1603 Figure 7 4 2645A A3 A D Converter PCA Assembly 2645A 1603...
Страница 258: ...2640A 2645A Service Manual 7 26 Figure 7 5 A4 Analog Input PCA Assembly 2620A 1604...
Страница 260: ...2640A 2645A Service Manual 7 28...