Download 505 Differential Analog Input Module

1.6
Using 20% Offset
Using the Module
with 20% Offset
Most applications use transducers that provide 1 to 5 volt (4 to 20 mA) input
signals instead of 0 to 5 volt (0 to 20 mA) input signals. You can allow for
this 20% offset by including some additional instructions in your RLL
(Relay Ladder Logic) program.
First, subtract 6400 from the input data word (WX). Then, multiply the
result by 125 and divide the product by 100. This yields the following
equation:
(WX–6400) x 125
––––––––––––––
100
= 20% offset data word
Consult your SIMATIC 545/555/575 Programming Reference User Manual
for information about the RLL instructions used in the conversion.
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Description
Differential Analog Input Module User Manual