Fluke 8845A Manual page 100

8845A/8846A
Programmers Manual
Loading Output Data
The output buffer is loaded when the Meter receives an output command, or when an
error occurs. Output commands are those device-dependent commands which load the
output buffer with data:
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•
•
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Because the Meter gives priority to input processing, it completely processes all
characters in the input buffer before it loads the output buffer. When the output buffer is
loaded, the Data Available bit in the serial poll register is set true.
Data from the output buffer is not actually loaded onto the IEEE-488 bus until the
controller addresses the Meter as a talker. This is done by sending the interface message
MTA (My Talk Address).
Types of Output Data
The types of data that can be loaded into the output buffer are shown in 7. Each type has
its own format. Error messages, which are loaded into the output buffer if an error
occurs, are formatted as numeric data.
Numeric Data and Error Messages
Numeric data is loaded into the output buffer in response to an instrument trigger. The
exponent is always a multiple of 3, as in engineering notation.
Numeric data is of constant length, It is 11 characters (plus terminators) when the suffix
is disabled, and 16 characters (plus terminators) when the suffix is enabled.
The suffix is enabled by the Y1 command, and consists of five ASCII characters as
shown in Figure 7. The suffix is appended only to numeric data, never to status data.
The terminators are determined by the Terminator commands. The default is CR LF EOI.
There are three types of numeric data: measurement data, overrange indication, and error
messages.
Overrange Indication
If a reading is overrange (≥200,000 counts), the measurement data has the following
format:
Overvoltage readings (> 1000V dc or 700V ac) do not result in this display.
Error Messages
If the Meter detects an error, it loads an error message into the output buffer in the
following numeric format:
The digits xx represent a two-digit error code. (Error codes are listed in Appendix A. The
suffix is always suppressed for error messages.
90
Get commands (G0 through G8)
Single-trigger command (?)
Group execute trigger (GET)
Continuous Trigger (T0)
±9.99999E+9 <suffix> <terminators>
+1.00xxE+21 <terminators>