8845A/8846A
Programmers Manual
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The trigger mode can be read using the G0 command. The Meter defaults to T0 on both
power-up and any device-clear command (*, DCL, or SDC).
Wn (Terminator Commands)
The Terminator commands select what terminators the Meter appends to every output
string. The available terminators are: Carriage Return (CR), Line Feed (LF), and End Or
Identify (EOI).
CR and LF are ASCII control codes, sent over the data lines just like output data. EOI is a
uniline message which is sent simultaneously with the last character in the output string.
Normally, each output string is terminated with CR followed by LF and EOI.
The terminator selection can be read using the G6 command. The Meter defaults to W0 on
power-up and any device-clear command.
X0 (Clear Error Register Command)
The X0 command clears the error status register of the Meter. After an X0 command is
executed, a G7 command (Get Error Status) would return 1000 (no errors).
Note that the error status register is also cleared when any device-clear command (*, DCL,
or SDC) is executed. However, X0 is useful for clearing the error status register without
forcing a complete instrument clear (as do the device-clear commands).
Yn (Suffix Commands)
The Suffix commands enable or disable a suffix which the Meter can append to all
numeric data. The suffix includes a comma, an overrange indicator (>), and a function
indicator (VDC, VAC, OHM, IDC, or IAC). The suffix is illustrated in Figure 7. An
example of suffixed data is given in the “Numeric Data and Error Messages” paragraph
later in this section.
To read suffixed data with a controller using BASIC, one can read the whole line into a
string variable and then convert the numeric part into a numeric variable. However, it is
much easier to read the numeric part directly into a numeric variable and the suffix into a
string variable. The leading comma of the suffix serves as a convenient delimiter. For
example, a BASIC program statement might be:
INPUT @1,A, B$
The suffix status can be read using the G6 command. The Meter defaults to Y0 on power-
up and any device-clear command (*, DCL, or SDC), unless in talk-only mode.
Z0 (Self-Test Command)
The Z0 command intiates the diagnostic self-tests.
Since the Meter is reset at the end of the self-tests, the Z0 command should be the last
command in a given command string. The Meter will ignore any subsequent commands
in the same command string.
When the self-tests are complete and no errors have occurred, the serial poll register will
have bit 5 (Data Available) true and bit 6 (Any Error) false.
Device Clear Command
The asterisk command (*) is a device-dependent message which resets the Meter to the
power-up default settings and clears all registers and buffers except for the input buffer.
The remote/local status remains unchanged. The asterisk command performs the
following:
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