Technician Handbook ! 673 Electronic & Computer Controlled Systems Advanced DVOM Some types of electrical measurements that are commonly made using an oscilloscope can be made using the advanced features of many DVOMs. The following are features of the Fluke 87 . Features MIN/MAX Recording When voltage is varying, sometimes the only measurements needed are the upper and lower voltage readings. On a CANL communication line, for example, communication signals create voltages between 1.5V and 2.5V. With the MIN/MAX Recording feature, the DVOM records and displays the minimum and maximum voltages to verify the voltage range. MIN/MAX is also helpful for identifying transient voltage spikes.
If a momentary 12V spike were to appear on the CANL communication line, the 12V MAX reading would indicate a problem. NOTE Set the voltage range before selecting MIN/MAX. If auto-ranging sets the initial range too low, the MAX readings will be O.L. Peak MIN/MAX By pressing the Peak MIN/MAX button (also called the “alert” button), you can toggle the sampling speed between 100 milliseconds and 1 millisecond. Any voltage signal lasting at least as long as the sampling speed is recorded. Relative Delta The Relative Delta function allows you to select a reference value, and then displays the difference between the current reading and the reference value.
This might be useful when looking for variations in voltage from a reference value. In bench testing for resistance , touching the leads together and selecting Relative Delta effectively deducts the resistance of the leads from component resistance measurements. 30 Technical Training