Chapter 1 Before You Start ...

Differences Between Prior and Current Revisions of the HP53131A/132AMeasurements

If your Counter contains other than the current firmware revision, the following measurement capabilities are different:

Ratio channel selections Ratio 2 to 1 and Ratio 3 to 1

(for those counters equipped with Channel 3) are not available.

Ratio “AUTO-armed” does not automatically extends gate to capture sufficient edges.

If Channel 1 input frequency is less than approximately 10 Hz, the Ratio gate time is not extended to capture sufficient Channel 1 edges to produce a valid measurement. Default gate time is 100 msec, which is not long enough to capture two edges on a low-frequency signal. The user is required to extend the gate by switching to TIME arming, and selecting a gate time appropriately long.

Sensitivity for firmware revision below does not have adjusted controls to LO and MED sensitivity.

In some Counters that contained firmware revision 3317,

LO sensitivity fails to correctly count very high frequency signals.

Statistics

If your Counter contains other than the current firmware revision s, single-shot statistics are not available using the ON SINGLE: menu item found in the Statistics menu (use Stats key).

HP-IB Commands[:SENSe]:EVENt[12}:HYSTeresis:RELative

If your Counter contains firmware revision s 3402 and below, the input hysteresis command and query does not operate in the conventional way. That is, [:SENSe]:EVENt[12]:HYSTeresis:RELative sets high sensitivity when the parameter is MINimum or 0 percent, and sets low sensitivity when the parameter is MAXimum or 100 percent.

In the prior firmware revisions (3317, 3335, or 3402), MINimum or 0 percent corresponded to low sensitivity, and MAXimum or 100 percent corresponded to high sensitivity.

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Programming Guide