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Using analog PACIO modules

There are several PACIO modules available that are designed for analog signal processing. These are:

Model Number Type Description
PACIO-441-01 AI4-mA 12 Bit Four single-ended 0..20mA or 4..20mA analog inputs.
PACIO-441-02 AI4/8-VDC 13 Bit Eight single-ended or four differential 0..10V or +/-10V analog inputs.
PACIO-442-02 AO4-VDC/mA 12 Bit Four 0..10V, +/-10V, or 0..20mA analog outputs.
PACIO-443-01 AI4-Pt/Ni100 16 Bit Four Pt/Ni100 temperature sensor or resistance measurement inputs.
PACIO-443-03 AI4-Pt/Ni1000 16 Bit Four Pt/Ni1000 temperature sensor or resistance measurement inputs.

These function blocks all read or produce analog signals as integer values, which means that the values must be scaled and converted to or from REAL or LREAL floating point formats in order to be truly useful. To make this easier, this FAQ includes a link to download a set of function blocks that show how this is done. Many users will be able to drop them into their programs without modification. The function block library can be downloaded here. The library comes with a basic example for each module showing how it should be used.


  • Some modules have Unipolar and Differential settings. If you are operating the module in Unipolar mode, set the bUnipolar input to TRUE on the helper block.
  • Test the full range of the analog input and make sure your program can properly read accurately read values from the entire range. If not, make sure you are operating the input or output in the right mode.
  • If you install the provided library, you can view the source code (great for debugging) by double-clicking the block after you put it into CFC or Ladder. In Structured Text, you can right-click it and click "Go to declaration".
  • If your measured voltage, current, or temperature value appear to be bouncing around, consider activating the filter built into each channel. This can help to stabilize the value. Some applications may also require additional grounding and noise-mitigation measures. PACIO modules can be equipped with a shield bond to enhance noise-immunity of shielded I/O cables. Model numbers for the shield bonds available are PACIO-412-01 (single position) and PACIO-412-02 (dual position). See page 138 of the PAC User Guide for more information.
  • Analog input and output modules all have multiple options for how they may be used. All of these options are implemented as simple state machines that can be triggered with the SetOptions bit in their PDO (Process Data Object) maps. By default, the units power up with all inputs and outputs disabled to prevent shorts. An example of how to enable them and set options can be found in the library download link given above.