Chapter 4 Features and Functions

Scanning

∙When you add a digital read (multifunction module) to a scan list, that port is dedicated to the scan. The instrument issues a Card Reset to make that port an input port (the other port is not affected).

∙While a scan is running, you can perform low-level control operations on any channels on the multifunction module that are not in the scan. For example, you can output a DAC voltage or write to a digital port (even if the totalizer is part of the scan list). However, you cannot change any parameters that affect the scan (channel configuration, scan interval, Card Reset, etc.) while a scan is running.

∙If a scan includes a read of the totalizer, multifunction module,

the count is reset each time it is read during the scan only when the totalizer reset mode is enabled (TOTalize:TYPE RRESet command or the Advanced menu for the totalizer).

∙If you install a module while a scan is running, the instrument will cycle power and resume scanning. If you remove a module while a scan is running, the instrument will cycle power and resume scanning (even if the removed module was part of the scan list).

∙You can use either the internal DMM or an external DMM to make measurements of your configured channels. However, the instrument allows only one scan list at a time; you cannot scan some channels using the internal DMM and others using an external DMM. Readings are stored in HP 34970A memory only when the internal DMM is used.

∙If the internal DMM is installed and enabled, the instrument will automatically use it for scanning. For externally-controlled scans, you must either remove the internal DMM from the HP 34970A or disable it (see “Internal DMM Disable” on page 145).

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