Fluke 2680A Service Manual page 50

268XA
Service Manual
2-2
Input Protection......................................................................................... 2-18
Input Signal Conditioning......................................................................... 2-18
Function Relays ........................................................................................ 2-18
Channel Selection Circuitry...................................................................... 2-19
DC Volts and Thermocouples Measurement Circuitry............................. 2-19
Ohms and RTD Measurement Circuitry ................................................... 2-20
AC Volts Measurement Circuitry. ............................................................ 2-22
Frequency Measurements ......................................................................... 2-23
Active Filter (ACV Filter) ........................................................................ 2-24
Voltage Reference Circuit ........................................................................ 2-24
Analog/Digital Converter Circuit ............................................................. 2-24
Autozero ................................................................................................... 2-24
Integrate .................................................................................................... 2-25
Deintegrate1.............................................................................................. 2-25
Deintegrate2.............................................................................................. 2-27
Overhead................................................................................................... 2-27
Inguard Digital Kernel Circuitry............................................................... 2-27
Open Thermocouple Detect Circuitry....................................................... 2-28
A4 Analog Input PCA Circuit Description ................................................... 2-28
A31 A/D Power Supply Circuit Description................................................. 2-29
Controller/System Power (Outguard) to A3 A/D Converter (Inguard)
Communications ........................................................................................... 2-29
Special Codes ................................................................................................ 2-29
Resets ............................................................................................................ 2-29
Commands..................................................................................................... 2-30
Perform Scan............................................................................................. 2-30
Perform Self-Test...................................................................................... 2-31
Return Firmware Version ......................................................................... 2-31
Return Boot Firmware Version................................................................. 2-31
Set Global Configuration .......................................................................... 2-32
Set Channel Configuration........................................................................ 2-32
Do Housekeeping...................................................................................... 2-32
Checksums .................................................................................................... 2-33
Errors............................................................................................................. 2-33
Power-Up Protocol........................................................................................ 2-33
Inguard Unresponsive ................................................................................... 2-33
Inguard Software Description ....................................................................... 2-33
Hardware Elements ....................................................................................... 2-34
Channel MUX........................................................................................... 2-34
Function Relays ........................................................................................ 2-35
Stallion Chip and Signal Conditioning ..................................................... 2-36
A/D ........................................................................................................... 2-39
DISCHARGE Signal ................................................................................ 2-42
Open-Thermocouple Detector .................................................................. 2-42
Channel Measurements ................................................................................. 2-42
Reading Rates ........................................................................................... 2-42
Measurement Types.................................................................................. 2-43
Autoranging .............................................................................................. 2-45
Overload ................................................................................................... 2-45
Housekeeping Readings ................................................................................ 2-45
Reading Types .......................................................................................... 2-45
Housekeeping Schedule............................................................................ 2-46
Self-Tests....................................................................................................... 2-47
Power-Up Self-Tests................................................................................. 2-47
Self-Test Command .................................................................................. 2-47