Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 118)

Chapter 7
Using Analog
7–4
The analog input circuits are able to monitor current and voltage signals and
convert them to digital data. There are six terminals assigned to the input
channels that provide two voltage inputs, two current inputs, and two return
signals (commons).
The analog outputs can support either a current or voltage function. There
are three terminals assigned to the output channels that provide one voltage
output, one current output, and a common (shared) terminal.
The following table shows sample Analog Signal and Data Word values
using the nominal transfer function formula:
N=I
in
x 32767/21 where I
in
(analog signal) is in milliamperes (mA)
N=V
in
x 32767/10.5 where Vin (analog signal) is in volts (V)
N=(I
out
– 4 mA) x 32767/16 mA where I
out
(analog signal) is in
milliamperes (mA)
N=V
out
x 32767/10V where V
out
(analog signal) is in volts (V)
Analog Signal Data Word
Input Output
0V 0 0
5V 15603 16384
10V 32107 32767
4 mA 6241 0
11 mA 17164 14336
20 mA 31207 32767
Converting Analog Input Data
Analog inputs convert current and voltage signals into 16-bit two’s
complement binary values.
To determine an approximate voltage that an input value represents, use one
of the following equations:
 input value ➀ =
input voltage(V)
10.5V
32,767
➀
The Input Value is the decimal value of the word in the
input image for the corresponding analog input.
For example, if an input value of 16,021 is in the input image,
the calculated value is:
10.5V
32,767
 16,201 =
5.1915(V)
It should be noted that the actual value may vary within the
accuracy limitations of the circuit.
Converting Analog Data