HP WaterSkis E1312A, WaterSkis E1412A manual General Guidelines for Increasing Measurement Speed

General Guidelines for Increasing Measurement Speed

Note

Avoid Function Changes

Avoid Aperture Changes

The following guidelines show how to increase measurement speed, which in some cases, will reduce the accuracy of the measurement. Some of the guidelines will not affect accuracy but simply make taking measurements more efficient. Be aware that these guidelines also increase the complexity of the program.

1.Avoid function changes.

2.Avoid aperture changes when making frequency or period measurements.

3.Minimize the number of command/response sessions.

4.Set autozero to ONCE or OFF.

5.Turn autorange OFF.

6.Decrease the NPLC setting for DCV, DCI, 2-wire and 4-wire resistance measurements.

7.Store the readings in the HP E1312A or HP E1412A internal memory instead of sending them directly to the computer.

Only items 4, 5 and 6 may reduce the accuracy of a measurement. The rest of the guidelines involve additional work by the system programmers.

The HP E1312A and HP E1412A Multimeter takes time to switch between the various functions because the hardware must be re-configured for the new function. Organize your program so all measurements on a function are done at the same time.

Changing aperture times for frequency or period measurements takes a significant amount of time. The easiest way to avoid aperture changes is to directly specify the aperture time. This requires that you not use the MEASure command and that you not specify the optional <resolution> parameter in a CONFigure command.

Minimize the

Number of

Command/

Response Sessions

Minimizing the number of command/response sessions involves programming the multimeter to pace itself, rather than the computer pacing the multimeter. Use the external trigger mode when measuring signals routed to the multimeter from a switch module.

The EXTernal TRIGger input can be used to start a scan from an external signal. The HP E1406 Command Module “Clk out” is a convenient source for an external signal. A potential problem exists whereby an external trigger arrives before the multimeter is ready to start a new scan causing the trigger to be missed and no error message generated. Send a *OPC? command to the multimeter after setting up the multimeter and prior to initiating the switch module to eliminate this problem.

196 Measurement Speed and Accuracy Trade-offs Appendix C