70Inputs/Outputs Menu8.4.5 Characteristics test8.5 Analog output characteristicsThere are three types of output• Linear• Tri-linear• None8.5.1 LinearThe "Linear" output is the default setting for the analog output. It is illustrated in Figure 37 below(4-20 mA output is shown, 0-20 mA or 0-5 V settings are similar).The goal of this setting is to use all the points available on the slope from 4 mA to 20 mA toshow the range of measurements that are usual in the measured process. Setting the outputthis way allows for the highest signal resolution for the actual conditions.The downside is that any measures below the set range will have the same analog signallocked at 4 mA. Similarly, any measure over the set range will have the same analog signallocked at 20 mA. Settings must made in balancing these aspects.SettingsFor the output, set ML and MH in the current measuring unit (e.g. °C for a temperature output).When a compound unit is selected the smallest unit will be used (e.g. ppb for a "ppm-ppb"compound unit).These points should be set keeping in balance the following conditions (Figure 37 above):• The smaller is Range 1, the better is the analog signal resolution within the expected rangeof measure.• In Range 0 the analog output only shows that measurement is below the ML value. Similarlyin Range 2 the analog output only shows that measurement is over the MH value.This is a test for the correct operation of the peripheralsconnected to each analog output, by verifying that the PLCcomputes the correct value.The analog output will send the current corresponding to thevalue entered in the text boxes.• Type in a test value for each analog output, and check forthe related action on the peripheral.Figure 37 “Linear” characteristics diagram
