Rockwell Automation 1769-IF4XOF2 Compact 8-Bit Low Resolution Analog I/O Combination Module - Manual (Page 50)

Publication 1769-UM008A-EN-P - November 2001
4-6 1769-IF4XOF2 Module Data, Status, and Configuration Channels
Input Data Resolution and Format
The following table identifies the current and voltage input ranges for
the 1769-IF4XOF2 module, and the number of significant bits
provided by the module with its single (non-programmable) filter. The
number of significant bits indicated in the table has little or no jitter
due to noise. The module’s RAW/Proportional data format presents
the value to the controller via a left justified 16-bit field, with the most
significant bit for the sign bit (which is always zero).
Input Scaling
Example 1: Find voltage by converting raw/proportional data values
To convert a raw/proportional data value to find the voltage
being measured:
Voltage = (Input Data Value X volts/significant bit) /
(counts/significant bit)
If input data value is 32,640
Voltage = (32640 X 0.04118V) / 128
= 10.50 Volts
Example 2: Find current by converting raw/proportional data values
To convert a raw/proportional data value to find the current
being measured:
Current = (Input Data Value X amps/significant bit) /
(counts/significant bit)
If the input data value is 31,104
Current = (31,104 X 0.08235A) /128
= 20 mA
Table 4.3 Input Data Resolution and Format
Full Input Range RAW/Proportional Data
Significant Bits Resolution per LSB Decimal Representation of Input Count Value
0V to 10.5V dc Sign + 8 bits 41.18mV 0 to 32640 128 (1LSB)
0 mA to 21 mA Sign + 8 bits 82.35mA 0 to 32640 128 (1LSB)