Fluke 8808A User Manual - Page 68

Sending Numeric Values to the Meter, Sending Command Strings to the Meter

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8808A Users Manual In some instances, a terminator is automatically transmitted at the end of the host's output string (the Meter's input string). Sending Numeric Values to the Meter Numeric values can be sent to the Meter as integers, real numbers, or real numbers with exponents, as shown in the following examples: +12345689 Sends the signed integer "12345689" -1.2345E2 Sends "-1.2345E2" or "-123.45" Sending Command Strings to the Meter Observe the following rules when you construct strings to be sent to the Meter over the computer interface: • Rule 1: Read meter's output buffer once for each query command. The Meter's output buffer is cleared after it has been read. This prevents previously read data from being read a second time by mistake. If you attempt to read the Meter's output buffer twice without an intervening query, the Meter will not respond to the second read. • Rule 2: Read query responses before sending another command string. Output data remains available in the output buffer until the host reads it or until the next command string is received by the Meter. This means the host must read the Meter's output buffer before the next command string is sent to the Meter. • Rule 3: The meter executes each command completely in the order received before moving on to the next command. If an input string contains a trigger, enter the commands in the following order: 1. Commands to configure the Meter (if any) 2. The trigger command 3. Commands to read the result of a triggered measurement (VAL?), or to reconfigure the instrument (if any) 4. The terminator Note If MEAS?, MEAS1? or MEAS2? is used, the command should follow Configure, Trigger. How the Meter Processes Output The following paragraphs describe how the Meter processes output. The Meter outputs an alphanumeric string in response to a query command from the host. (Query commands end with "?".) Output strings for RS-232 applications are terminated with a Carriage Return and Line Feed (). After sending the Meter a command via the RS-232 interface, wait for the Meter to return a prompt before sending another command. Failure to do so causes a device-dependent command error, and the second string is discarded. Numeric output from the Meter is shown in the following examples: +1.2345E+0(format 1) Measured value of 1.2345 4-8

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8808A
Users Manual
4-8
In some instances, a terminator is automatically transmitted at the end of the host’s output
string (the Meter's input string).
Sending Numeric Values to the Meter
Numeric values can be sent to the Meter as integers, real numbers, or real numbers with
exponents, as shown in the following examples:
+12345689
Sends the signed integer “12345689”
-1.2345E2
Sends “-1.2345E2” or “-123.45”
Sending Command Strings to the Meter
Observe the following rules when you construct strings to be sent to the Meter over the
computer interface:
•
Rule 1: Read meter's output buffer once for each query command.
The Meter’s output buffer is cleared after it has been read. This prevents previously
read data from being read a second time by mistake. If you attempt to read the
Meter’s output buffer twice without an intervening query, the Meter will not respond
to the second read.
•
Rule 2: Read query responses before sending another command string.
Output data remains available in the output buffer until the host reads it or until the
next command string is received by the Meter. This means the host must read the
Meter’s output buffer before the next command string is sent to the Meter.
•
Rule 3: The meter executes each command completely in the order received before
moving on to the next command.
If an input string contains a trigger, enter the commands in the following order:
1.
Commands to configure the Meter (if any)
2.
The trigger command
3.
Commands to read the result of a triggered measurement (
VAL?
), or to
reconfigure the instrument (if any)
4.
The terminator
Note
If
MEAS?
,
MEAS1?
or
MEAS2?
is used, the command should follow
Configure, Trigger.
How the Meter Processes Output
The following paragraphs describe how the Meter processes output. The Meter outputs an
alphanumeric string in response to a query command from the host. (Query commands
end with “?”.) Output strings for RS-232 applications are terminated with a Carriage
Return and Line Feed (<CR><LF>).
After sending the Meter a command via the RS-232 interface, wait for the Meter to return
a prompt before sending another command. Failure to do so causes a device-dependent
command error, and the second string is discarded.
Numeric output from the Meter is shown in the following examples:
+1.2345E+0(format 1)
Measured value of 1.2345