Analog Inputs
Original instructions
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Overview
This section describes how to interpret the value of the analog input channels.
Key
This section describes input words 1 ... 16, as highlighted in the table below:
Word
Input Data
Output Data
1 = LSW
Value, input channel 1
Parameters for input channels 1 ... 4
2
Value, input channel 2
Parameters for input channels 5 ... 8
3
Value, input channel 3
Parameters for input channels 9 ... 12
4
Value, input channel 4
Parameters for input channels 13 ... 16
5 ... 15
Value, input channel 5 ... 15
Not used
16
Value, input channel 16
Not used
Bit Assignments
The following table tells how bits are assigned:
Analog-to-digital conversion
Carried out on 12 bits + sign
Bit 15
Sign bit
Bits 14 ... 3
Input channel values
Bits 2 ... 0
Unused. Because these bits are always 0, the value of the word changes in increments of 8
Analog Input Values
Mapping of analog input values is shown below.
Broken Wire Indication
Broken wire detection is possible for the 4 ... 20 mA range. In this case, a current signal that is less than 1 mA on one of the inputs is detected as a broken wire. The input word of that channel returns the value -32,768. A broken wire indication has the following binary format: