Keithley 6512 Instruction Manual page 66

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2.
3.
4.
Keep in mind that you can program the instrument to assert SRQ under any of these conditions
simply by setting bit 5 in the SRQ mask (M32X). Paragraph 3.2.13 describes how to use the U1
command to obtain information on the type of error from the instrument. The U1 command is
used to clear the error bit and restore operation of SRQ on error after the error byte is read.
Programming
1.
Notes
2.
3.
Examples
M3X
M40X
M32X
An illegal device dependent command (IDDC) or illegal device dependent command op-
tion (IDDCO) was transmitted.
The instrument was programmed when not in remote.
A trigger overrun has occurred (the instrument was triggered while processing a reading
from a previous trigger).
A number error has occurred (a calibration value was out of limits).
Note that the status byte should be read to clear the SRQ line once the instrument has
generated an SRQ. All bits in the status byte will be latched when the SRQ is generated. Bit
6 (RQS) will be cleared when the status byte is read.
Even with SRQ disabled, the status byte can be read to determine appropriate instrument
conditions. In this case, bits 0, 1, 3, and 4 will be continuously updated to reflect current
instrument status; however, bit 5 (the error bit) will latch and remain so until the U1 status
word (paragraph 3.2.13) is read, even if no SRQ occurs.
See Appendix D for an example program that demonstrates SRQ and serial polling.
SRQ on reading overflow and data store full.
SRQ on reading done and on error.
SRQ on error only.
IEEE-488 Programming
3-11