CHAPTER 4 DIGITAL MULTIMETER Relative A relative mode shows the difference between the last value measured and the current value. This shows the change in value, rather than the absolute value. Some multimeters have this feature. Offset An offset mode shows the difference between the value stored in memory and the current value being measured. Some multimeters have this feature. Limit Testing/Compare A limit mode displays whether the measured value exceeds a specified maximum or minimum value stored in memory. Some multimeters have this feature. Holster or Rubber Boot A rubber boot (see Figure 4-14) protects the meter from scuffs and bumps that might otherwise damage or crack the meter's primary case. The meter is almost always operated with the boot installed, unless space is a serious issue. Figure 4-14. Rubber boot (edge cover) for meter If a rubber boot is available but not included with the meter, it might be best to purchase the boot at the same time as the meter. The boot may no longer be available when the meter is discontinued. Most multimeters have a boot available. AC Features Unlike DC (Direct Current) that comes from a battery, AC (Alternating Current) comes from a standard household outlet. Because of the danger from the higher voltage and current capacity of household outlets, this book only involves DC. 44