Typical Ieee 488 Input Strings; Sending Numeric Values To The Meter; Sending Command Strings To The Meter - Fluke 8845A Programmer's Manual

Typical IEEE 488 Input Strings

Two typical strings that could be sent to the Meter over the IEEE 488 interface are shown
in Figure 2. These strings are written in Fluke BASIC to be sent from a Fluke 1722A
Instrument Controller.

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:
EXAMPLE
+12345689
-1.2345E2

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 ONLY 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 QUERY
COMMAND STRING.
Output data remains available in the output buffer until read by the host or until the
next command string is received by the Meter. This means the Meter's output buffer
must be read by the host before, rather than after, 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, that
is, from left to right, as written:
1. Commands (if any) to configure the Meter.
2. The trigger command.
3. Commands to read the result of a triggered measurement (FETCh? or READ? for
the 884XA and VAL? for the Fluke 45 emulation), or to reconfigure the
instrument (if any).
4. The terminator.
Figure 2 gives two examples of a command string for the Meter. The first example is a
command recognized by the Meter in the 8845 or 8846 command mode. The second
example is for the Fluke 45 command mode.
EXPLANATION
Sends the signed integer +12345689
2
Sends -1.2345 x 10
Digital Multimeter
How the Meter Processes Input
19