Introduction
This chapter contains informat i on about measures to be taken
for keeping the instrument in operative condition, or in other
words, what you can do to maintain the measurement accu
-
racy, improve certain characteristics and prevent a break
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down.
Traditional troubleshooting is described in Chapter 6 - Repair.
Calibration
The single most important factor for maintaining the high per
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formance of your instrument is calibration on a regular basis.
A timer/counter is mainly used for time/frequency-related
measurements, so knowing the characteristics of your
timebase reference is vital to reliable results.
Scheduled calibration of the b u ilt-in timebase reference is
highly recommended in applications where external, more ac
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curate, frequency references are not available. Suitable cali
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bration intervals depend on the chosen timebase option and
the acceptable inaccuracy, but once a year is often a good
starting point.
The '90' has also limited voltage measurement cap ab ilities,
and when these features are utilized, the voltage reference
should also be calibrated, preferably at the same time as the
frequency reference.
Both frequency and voltage calibration can be performed
without removing the cover, and the procedures are described
in Chapter 7, where you can also find information about cal-
culating calibration in tervals for different timebase refer-
ences.
Instructions for Firmware
Upgrade
The firmware is stored in a FLASH PROM, so it is possible to
upgrade via one of the standard instrument interfaces (GPIB
or USB) without opening the case. USB is standard on most
PCs, but GPIB communication r equires a special controller
board and dedicated SW from NI or CEC. A 'readme.txt' file
contains information not covered by these instructions. The
relevant files are available through the service organizati on.
–
Make sure the National Instruments NI-VISA 3.2 or
later is installed with USB support, even though you are
going to use the GPIB interface for the upgrade.
–
Establish a communication link between your PC and
the instrument over GPIB or USB by using a dedicated
application program, for instance NIMax from National
Instruments. No other instruments should be connected
to the same bus. Firmware upgrade over USB works
with firmware version V1.07 or above installed in the
instrument.
–
Send *IDN? to the instrument and watch the response.
If the ID string is OK you can exit the communication
program and start the upgrading procedure.
–
Download the latest firmware file (example name:
CNT_90_109_csl.hex) and the latest loader SW (exam
-
ple name: Loader.exe) to a common directory on your
PC.
–
Start the Loader.exe program.
–
Press "Load" to open the firmware file. Follow the in
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structions on screen. The update is automatic, and pro
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cess information can be seen on the PC screen as well as
on the instrument display. Do not interrupt the process
too early as it may take between a few minutes up to an
hour, mostly depending on different possible hardware
combinations. A thermometer indicator on the PC moni
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tor gives status reports. The crucial part of the process is
when the message "FLASH updating (uninterruptible)"
is displayed. Do not under any circumstances interrupt
the loader while this message is visible. If the process
fails during this part, it may be impossible to control the
instrument from the bus as well as from the front panel.
Then you have to load new firmware over the JTAG
connection to the processor, a method that only the fac-
tory can apply.
– After a successful update, the counter is reset (if previ-
ous firmware is V1.01 and above). The message "Firm-
ware update complete. Loader is trying to connect to the
counter again" is displayed on the PC monitor. Confirm
by pressing OK.
– Press OK again when the message "Counter found" is
displayed.
–
Press EXIT to leave the loader program.
–
If the counter is not reset by the Loader program, turn
the counter off and on when the update is complete.
NOTE 1: With some firmware revisions and GPIB cards the
Loader gives an error message:
"Counter I/O error. Loader shutting down" after the
successful update. This is a loader fault and does not
harm the upgrade process.
–
To remove the SRQ indicator on the front panel, which
might be present in such cases, start a GPIB communi
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cation tool and send the command "*PSC 1" and run a
full power cycle (OFF/ON).
NOTE 2: Some firmware revisions need a full power cycle to
resume proper operation. If the instrument does not
measure correctly after firmware upgrade, turn the in
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strument OFF and ON to initialize the hardware prop
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erly.
–
After the update, enter the calibration menu (password
62951413) and run "Calibrate internals".
5-2 Introduction
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