HP E1351A, User Manual

Page: 95 / 107

The number of readings specified in sample count will now be taken. If the
sample count is more than one scan, the scan list will start over again.
5. The voltmeter is now taking data which is being stored in the HP
E1326B hardware FIFO. With the 10
µ
sec aperture set, 512 16-bit readings
will collect here. In any other aperture only 256 32-bit readings will collect.
If you specified more than 512 readings, the computer needs to be removing
them from the FIFO while readings are being taken. The DVM FIFO is
connected to the HP E1326B VXI DATA BUFFER register.
To read the FIFO check the Data Ready bit in the Status Register to
determine if valid data is in the Data Buffer. Or, read the Data Buffer and
throw away any -1 readings, as a -1 decimal reading or all bits set to "1"
indicates invalid data. Keep reading the Data Buffer until you receive the
number of readings specified in Sample Count. Convert the readings from
voltmeter format to 32-bit real format.
6. To do debugging with the HP E1326B voltmeter, use the Query
Opcodes in Table B-1. This will verify that you have set the correct
parameters. Use the Send Error command (15) to get error codes back.
Refer to Table B-2 on page 98.
With the HP E1351A you cannot read back the contents in the FIFO,
therefore, debugging is difficult. Do verify that you get correct data back
from the Manufacturer ID Register and Device Type Register.
Appendix B HP E1351A/53A Register-Based Programming 95