Calibration
Introduction
5
5-3
Introduction
This section of the Service Manual provides a complete set of manual calibration
procedures for the 2680A/2686A. The calibration procedures are performed periodically
as well as after service or repair. There are no calibration procedures for the
2680A/2686A chassis nor for the DIO module. Only verification tests are run on those
items. The calibration is only performed on the analog A/D modules such as the precision
A/D input module (PAI) and the fast A/D input module (FAI).
Calibration
The 2680A/2686A device features module calibration that is performed over the RS-232
interface using ASCII characters. It is not necessary to open the module case. Each
analog A/D module must be calibrated separately. Using known reference sources,
closed-case calibration has many advantages. There are no parts to disassemble, no
mechanical adjustments to make, and the module can be calibrated by an automated
calibration system. The modules should normally be calibrated on a regular cycle,
typically every 90 days to 1 year. The chosen calibration cycle depends on the accuracy
specification you wish to maintain. The module should also be calibrated if it fails the
performance test or has undergone repair.
The calibration mode requires initialization through a built-in calibration command. To
enter the calibration mode, use the command CAL_MODE SPLUNGE. When calibration
is enabled, the secondary display shows ’CAL’. To disable the calibration mode, enter
CAL_MODE OFF. If you have entered calibration and wish to exit, send CAL_MODE
OFF, or just turn the device power off. You cannot stop calibration by entering front
panel commands.
Once the device is in calibration mode, closed-case calibration is made for the four
calibration groups as follows:
•
Volts DC
•
Volts AC
•
Resistance
•
Frequency
Once begun, each group must be completed successfully for the results of the calibration
to be made permanent. It is not necessary to perform all calibration groups.
Methods of Calibration
•
Calibration takes place using a host computer in a terminal mode. With this method
all commands and responses are considered individually.
•
Calibration uses the device RS-232 serial interface. It is possible to develop an
automatic calibration routine using the RS-232 commands. Procedures cannot be
performed over the network interface or from the device front panel.
Preparing for Calibration
Complete the following procedure to prepare for calibration.
1.
Connect the device RS-232 serial port to a host computer COM serial port as shown
in Figure 5-1. The “RS” cables used are standard null-modem cables (reversed
transmit and receive lines) that may be ordered from Fluke.
Summary of Contents for 2680A
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Page 207: ...Replaceable Parts Parts Lists 7 7 13 2680A DIO alg100f eps Figure 7 3 DIO Module ...
Page 209: ...Replaceable Parts Parts Lists 7 7 15 2680A FAI alg102f eps Figure 7 4 FAI Module ...
Page 211: ...Replaceable Parts Parts Lists 7 7 17 2680A PAI alg103f eps Figure 7 5 PAI Module ...
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Page 215: ...8 3 8 Schematic Diagrams Figure 8 1 Backplane PCA 2680A 4001 ...
Page 216: ...268XA Service Manual 8 4 Figure 8 1 Backplane PCA cont 2680A 1001 ...
Page 217: ...8 5 8 Schematic Diagrams Figure 8 2 Controller System Power PCA 2680A 4004 ...
Page 223: ...8 11 8 Schematic Diagrams Figure 8 3 Digital I O PCA 2680A 4006 ...
Page 224: ...268XA Service Manual 8 12 Figure 8 3 Digital I O PCA cont 2680A 1006 1 of 3 ...
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Page 227: ...8 15 8 Schematic Diagrams Figure 8 4 Backplane Extender PCA 2680A 4009 ...
Page 228: ...268XA Service Manual 8 16 Figure 8 4 Backplane Extender PCA cont 2680A 1009 ...
Page 229: ...8 17 8 Schematic Diagrams Figure 8 5 Extender PCA 2680A 4010 ...
Page 230: ...268XA Service Manual 8 18 Figure 8 5 Extender PCA cont 2680A 3010 ...
Page 231: ...8 19 8 Schematic Diagrams Figure 8 6 A D Supply Assembly 2680A 4031 ...
Page 232: ...268XA Service Manual 8 20 Figure 8 6 A D Supply Assembly cont 2680 1031 ...
Page 233: ...8 21 8 Schematic Diagrams Figure 8 7 PCMCIA PCA 2680A 4041 ...
Page 234: ...268XA Service Manual 8 22 Figure 8 7 PCMCIA PCA cont 2686 1041 ...
Page 235: ...8 23 8 Schematic Diagrams Figure 8 8 Output PCA 2680A 4062 ...
Page 236: ...268XA Service Manual 8 24 Figure 8 8 Output PCA cont 2680A 1062 ...
Page 237: ...8 25 8 Schematic Diagrams Figure 8 9 A D PFE PCA 2640A 4003 ...
Page 238: ...268XA Service Manual 8 26 Figure 8 9 A D PFE PCA cont 1 of 6 ...
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Page 244: ...268XA Service Manual 8 32 Figure 8 10 A D FFE PCA 2645A 4003 ...
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Page 250: ...268XA Service Manual 8 38 Figure 8 10 A D FFE PCA cont 700p29_topress zip 2645A 1003 6 of 6 ...
Page 251: ...8 39 8 Schematic Diagrams Figure 8 11 Analog Input Connector PCA 2620A 4004A ...
Page 252: ...268XA Service Manual 8 40 2620A 1004 Figure 8 11 Analog Input Connector PCA cont ...
Page 253: ...8 41 8 Schematic Diagrams Figure 8 12 Display PCA 1 of 1 ...
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