Ontrol's P-ION is a robust, general-purpose programmable controller to manage a variety of building systems including heating, ventilation, air-conditioning (HVAC) systems. The P-ION is distinguished from competition by several unique features, such as flex type input/output terminals, extreme protection against faulty connections, unmatched installer-friendly terminal configuration and others. A special emphasis on Niagara Framework compatibility is another important feature of this device. 

Communication Ports / Open Protocols

The P-ION can communicate simultaneously over TCP/IP and/or RS485 busses, using a variety of open protocols.

The RS485 port is commonly used for pulling in extra data points from local devices (e.g. frequency drives, IO modules...) or connecting a local display.


Unique I/O Features

  1. All inputs and outputs are protected against short circuits to ground and direct connection up to 50 VAC.
  2. Inputs and outputs are individually equipped with 3-wire plug-in terminals for 0V reference and 24V power distribution. No more messy jumpering between terminals.
  3. LEDs indicate short-circuit, open-circuit, fault or on/off status on each input & output.

16 Universal Inputs

All universal inputs can be configured as analog or voltage-free digital inputs.

Analog inputs are optimized for resistive type temperature sensors (e.g. PT1000) and 0-10 VDC devices. 13 bit A/D converters assure high-resolution measurements. For 4-20 mA input signals, external 500 Ohm resistors are required.

16 Flex Points

All flex I/O points can be configured as analog output, digital input or pulse input.

Analog outputs are used to control 0(2)-10V valve and damper actuators, humidifiers, frequency drives, etc. Convertor relay boards can be used to drive on/offloads.


Optimized for Niagara Framework

The P-ION is a universal programmable controller that can be deployed on any BACnet or Modbus compatible system.

But it was designed specifically to shine within Niagara Framework. Full programmability from within Niagara Workbench is a major advantage. A custom driver allows remote programming over the network. 

Smart BACnet IP and Modbus TCP drivers allow discovery and addition of any property of any component in the configured logic.

Universal Engineering Tools

The P-ION can be programmed by multiple tools.

In addition to the Niagara4 driver and programming tool, Ontrol is developing an independent browser-based programming interface. This tool will provide control logic programming, provisioning, backup and restore functionality.

P-ION is also compatible with third-party Sedona engineering tools developed by others.


RK4 Relay Module extension

The P-ION can be extended with RK4 relay modules to enable on/off switching of loads. One RK4 provides 4 independently switchable relays. For each relay, both normally-open and normally-closed contacts are available for wiring. LEDs indicate status of the relays and supply voltage.

Multiple RK4 modules can be connected to a P-ION, using two modes of operation.

Ribbon-Cable Connection

Up to two RK4 modules can be daisy-chained on a P-ION with a ribbon cable connection. Ribbon cable connectors are on the bottom of the module, allowing the cable to lie flat in the DIN rail.

This connection doesn't waste any of the physical I/O on the P-ION. So the 8 relays extension are an addition to the 32 points already existing on the controller.

Analog Control

The relays on the RK4 can also each be controlled by a 0-10 V signal. In this mode, the RK4 is a general-purpose analog-to-digital converter that can be used with any BMS controller. Therefore, any of the 16 flex points on the P-ION can be used to drive the relays on a RK4.

Benefits of P-ION
Versatile I/O Mix

P-ION provides 32 versatile physical points on a small foot-print.

The 16 universal inputs can be configured as analog or voltage free digital inputs.

The 16 flex points provide unique flexibility, being configurable as analog outputs or digital inputs!


The P-ION can be extended in multiple ways. The optional RK4 modules provide up to 8 relay outputs with a simple ribbon cable connection. 

The auxiliary RS485 port can be used to pull-in extra data points (e.g. from frequency drives, IO modules...) to be used in internal control logic and/or passed onto a supervisory system.

Local display option

Ontrol's R-ION color touch-screen displays can be interfaced to the RS485 port as a rich, fully configurable local user-interface.

more info


Extreme protection on all inputs and outputs against faulty connections (up to 230 Vac!) ensures ease-of-mind in difficult site conditions and when under pressure to complete installation.

Open protocols

The P-ION supports industry-standard open protocols including BACnet IP, Modbus TCP and Modbus RTU communications.

Multiple Programming Tools

The P-ION can be programmed by multiple software tools provided by Ontrol and others.

A Niagara4 driver and programming interface is available. As an alternative, Ontrol also provides an independent browser-based tool with full functionality for control logic programming, provisioning, backup and restore capabilities.

Installer Friendly

Exceptionally high I/O Density

24Vac and ground distribution terminals enable neater, simpler control panels.

Extreme protection against faulty connections (up to 230 Vac)


Flex IO points are a unique feature that provide extreme flexibility. These special type of points can be configured as analog output, digital input or pulse input. Whatever needs arise during project execution, you'll almost always be able to use the spare points on the P-ION.


All inputs and outputs are heavily protected against faulty connections (up to 230 Vac). It would take some ingenuity to break this controller.

Data Sheets

PION Calculator

Input/output requirements:
Required P-ION count
Required RK Count
Total length of modules