Computer Interfaces; Optimizing System Speed For Io Operation - Fluke 8845A Programmer's Manual

Computer Interfaces

Both the 8845A and 8846A Multimeters come equipped with an RS-232, Ethernet, and
IEEE 488 interface. Only one remote interface can be enabled at a time. Using any of the
interfaces turns the Meter into a fully programmable instrument that can be integrated
into an automated instrumentation system. For a PC with only USB ports, Fluke makes a
cable (Fluke PN 2675479) that converts between USB and RS-232 ports.
The remote interface port and settings can be changed only through the
Meter's front-panel controls.
Enabling or selecting a port for remote operation is a separate process from setting the
various parameters associated with a remote interface. An interface does not have to be
selected to set its parameters; the baud rate of the RS-232 port can be set while the Meter
has the LAN port enable, as the remote control port.

Optimizing System Speed for IO Operation

Several factors affect the remote system speed of the 8845A/46A. To make the fastest
measurements, it is best to store the measurements in internal memory before transferring
across the IO bus. This is particularly true if you want to collect a large number of
samples per measurement. Set up all of the parameters (i.e. function, range, filters, etc...)
prior to the measurements. Use the internal trigger. Set the trigger delay to zero. Turn off
the display. If operating with RS232, use the fastest baud rate available. The commands
that will run the fastest are the "INIT" and "FETCH?" combination.
One example of taking the fastest voltage readings is:
*cls
conf:volt:dc 0.1
volt:dc:nplc 0.02
zero:auto 0
trig:sour imm
trig:del 0
trig:coun 1
disp off
syst:rem
samp:coun 100
:INIT; *OPC?
:FETCH?
For any sample count greater than 1, measurements are returned comma
separated.
Note
# This clears all error prior to initiating readings
# Set the DC range to manual and 100 mV.
# Set the NPLC to faster reading rate 4 1/2 digits.
# Turn Autozero off.
# Set immediate trigger.
# Set trigger delay to zero.
# Set trigger count to one or specify a larger number.
# Turn display off. This may slightly improve reading rate.
# Put the 8846 in remote. Only needed for RS-232 or Ethernet
#(required for READ?)
# Set the sample count from 1 to 5000.
# "*OPC?" returns 1 indicating that the measurements have been
taken and are ready to be transferred to the computer using the
FETCH? command.
Note
Optimizing System Speed for IO Operation
Digital Multimeter
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