HP 34970A Totalizer Errors

Chapter 8 Tutorial

Multifunction Module

∙You can control when the totalizer actually records counts by providing a gate signal (G and G terminals on the module). A TTL high signal applied to the “G” terminal enables counting and a low signal disables counting. A TTL low signal applied to the “G” terminal enables counting and a high signal disables counting. The totalizer only counts when both terminals are enabled. You can use either the G terminal, the G terminal, or both. When a gate is not connected, the gate terminal floats to the enabled state, effectively creating a “gate always” condition.

Input Signal

(Rising Edge)

Gate Signal

(High True)

Totalizer Input

Add to Total

Totalizer Errors

∙Noise on the totalizer input can be a problem, especially on signals with a slow rise time. This noise can create a false indication of a threshold crossing. For more information on cabling noise, see page 335.

∙Contact bounce on external switches can create false counts.

All mechanical switches bounce when they open and close. Use an external capacitor to filter the contact bounce.

+5 V	Switch	Noise cause by bounce
	Closed	creates a false count

Limit Switch

Totalizer

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