Reading The Unit's Output Data; Disabling The End Or Identify (Eoi) Statement; System Output Mode; Home Command - HP 3456A Operating And Service Manual

Operation
Second Byte
Third Byte
••
Fourth Byte
The sign (polarity) is indicated with " + " as a "0" and
" I " .
" -" as a The exponent and the measurement digits
are in packed Binary Coded Decimal (BeD). The
decimal point is implied to the overrange digit's left .
The End or Identify (EOI) line is normally set prior to
the 4th byte.
Overload Output S
3-181.
PUt Statement in the Packed Format follows the same
number convention as the ASCII overload statement.
The difference is that the numbers representing the
overload condition is output in the Packed mode.
Reading
3-182. Multiple
ed between the readings with the End or Identify (EOI)
being suppressed. The EO) will not be activated until all
readings are output.
U g
the Packed Output. Since only four
3-183. npackin
bytes of data is output in the Packed Format, some sorl
of unpacking should be done for the reading(s) to make
sense. This is done simply by converting each 8 bil
binary number to a decimal number. An unpacking pro­
gram using Enhanced Basic (9835A/B. 9845B Con­
troller language) is in Appendix A.
3·1 84. Reading the 3456A's Output Data.
3-185. First choose the output format you wish to use.
The ASCII Format is chosen in this example. To output
data, the 3456A has to be addressed to "talk" and the
device receiving the data is the listener. Here is an exam­
ple.
a. HP-IB Format.
3-26 Rev B
0
tateme nt . The Overload Out­
Output. No delimiters are us­
b. HPL (9825A Controller Language) .
red 722,A
c. Enhanced Basic (9835A/B, 9845B Controller
Language).
ENTER 722;A
NOTE
Although it is not specified in the HP-IS
Format, the output oJ the 3456A is normally
stored in a variable. This
variable " A " is used in the controller
language examples.
3·186. Disabling the End or Identify (EOI) Statement.
3-187. The End or Identify (EOI) statement can be
disabled over the HP-IB for a faster transfer of
readings. This is done by sending program codes
to the 3456A using the programming procedure in
Paragraph 3-165. Disabling the EOI statement and us­
ing the 3456A's Internal Trigger mode allows the faster
possible reading transfer. The EOI statement is enabled
by sending codes "01" and at turn-on.
3·188. System Output Mode.
3-190. With the 3456A's System Output Mode enabled,
a new measurement cycle is not initiated until the pre­
sent reading is output by the instrument. The reading is
output by addressing the 3456A to "talk". Once this is
done, a new measurement cycle is started. As long as the
System Output mode is enabled and no reading is out·
put, the instrument does not take any new readings. The
mode is an advantage when using controllers slower
than the 3456A. For example, if the Number of
Readings per Trigger operation is selected to output
readings. the readings are output one after another. A
slow controller may not be able
the 3456A's output speed and loose some or all
readings. The System Output mode prevents this from
happening. The 3456A waits until the controller is able
to receive data. The mode is enabled by sending pro·
gram codes "SDI" and disabled by codes "SOO". Use
the programming procedure in Paragraph 3-165 to send
the codes.
3·191. Home Command.
3-192. The Home Command is used to reset the 3456A
to the same conditions as sending Ihe CLEAR message,
except faster. The differences between Home, Clear.
Reset, and Turn·On are listed in Table 3-6. The Home
Command is sent by program code "H" using the pro­
gramming procedure in Paragraph 3-165.
Model 3456A
is
the reason why
"00"
accept the readings at
10
,.,