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5-57. Error Queue
When a command error, execution error, or device-dependent error occurs, its error code
is placed in the error queue where it can be read by the ERR? command. (See
Appendix F for a list of error messages.) A way to decode an error code is to send the
command, EXPLAIN?, which returns a description of a error code. Reading the first
error with the ERR? command removes that error from the queue. A response of 0 means
the error queue is empty. The Error Available (EAV) bit in the Serial Poll Status Byte
indicates whether the queue is empty. The error queue is cleared when you turn off the
power, and when you use the *CLS (Clear Status) common command.
The error queue contains up to 16 entries. If many errors occur, only the first 15 errors
are kept in the queue. A 16th entry in the queue is always an "error queue overflow"
error, and all later errors are discarded until the queue is at least partially read. The first
errors are kept, because if many errors occur before the user can acknowledge and read
them, the earliest errors are the most likely to point to the problem. The later errors are
usually repetitions or consequences of the original problem.
5-58. Remote Program Examples
The following programming examples illustrate ways to handle errors, to take
measurements, take a number of successive readings, lock the range, and calibrate the
calibrator. These excerpts from programs are written in DOS BASIC.
5-59. Guidelines for Programming the Calibrator
Commands are processed one at a time as they are received. Some commands require a
previous condition be set before the command will be accepted by the 5820A Calibrator.
Using the following programming guidelines will insure that the output is programmed to
the desired state.
•
The SCOPE command should be programmed first.
•
The output should be programmed next with the OUT command.
•
All other output parameters such as offset and waveform should be programmed
next.
•
The error status should be checked with the ERR? command. The calibrator will not
process the OPER command if an unacknowledged error exists.
•
Finally, the calibrator should be placed in operate with the OPER command.
A controller program first needs to initialize the interface and the 5820A Calibrator.
Refer to following sample program:
10 INIT PORT 0 \ REMOTE @6
20 PRINT @6, "*RST;SCOPE VOLT; OUT 1v, 0HZ;;OPER" ! RESET THE 5820A,
If you wish to use SRQs, first use the *SRE, *ESE, and ISCE commands to enable the
desired event. Refer to "Checking 5820A Status."
Remote Operation
Remote Program Examples
! PUT THE 5820A INTO THE
! REMOTE STATE
! PROGRAM IT TO OUTPUT
! 1 V DC
5
5-45
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