Industrial IO Modules: DIN-Rail RTU Controllers with Modbus, MQTT and SNMP

What is Industrial IO Monitoring?

Industrial IO monitoring solutions track and manage input/output (DIO) signals from industrial equipment and systems including sensors (temperature, humidity and water leakage for example), actuators, switches, valves, motors, and energy meters, and the control systems including PLCs, SCADA and DCS systems that automate an industrial facility.

The function of an industrial IO monitoring device is to collect signals and data to provide a real-time operating status for the facility including measurements, readings, the ON/OFF state of devices, and alarms, and to route that data over industrial networks using SNMP, Modbus, Ethernet/IP, Profinet and other protocols to a central control room dashboard or cloud-based application. The telemetry information provides the core data for industrial automation, process control and remote asset condition monitoring. Typical industries include manufacturing, oil and gas, water treatment, and utilities where equipment is spread across large or hard-to-reach sites including mega and hyperscale data centre facilities.

Types of IO Modules

There are two core types of IO module: Digital and Analog.

• Digital IO Modules: Digital input (DI) modules receive digital inputs from third party devices including signal/dry contacts. Digital output (DO) modules can provide ON/OFF signals to devices including switches, pushbuttons, indicator lights, and simple valves. Digital outputs can be relay or solid-state.
• Analog Modules: receive analog information from connected sensors. Examples include AC and DC measurements such as voltage, frequency, current, temperature, flow and pressure.

Local and Distributed IO Modules

Local IO modules mount directly onto a backplane (usually via DIN rail) and are installed next to a central PLC (programmable logic controller). Signals are transmitted back to the local IO module. Distributed IO is similar to the Edge computing concept. In a distributed architecture, the DI/DO module is installed in the field, close to the device or machinery to be monitored or controlled. The cabinets used to house the DI/DO modules are either IP20 (standard) or a more rugged version for field deployments such as IP67 which provides protection from dust and water ingress and vibration.

For information transmisson fieldbus and serial comms may be used including: Modbus/RTU (RS485) or PROFIBUS, or industrial ethernet including EtherCAT, PROFINET, Ethernet/IP or Modbus/TCP.

Perseus Industrial Scalable Industrial DIN-rail I/O Modules

The Perseus Industrial 310 and Perseus Industrial 315 units have as standard 5 Digital Inputs (DI) volt-free/dry contacts with S0 pulse counters and 2 Digital Outputs (DO) relays.

DIN rail RTU-Expanders can be added to expand the number of DI contacts and DO relays to meet the needs of the application project.

The Perseus Open API and Integrations: Modbus/RTU, MQTT and SNMP

Perseus Industrial controllers are designed to work alongside your existing systems, not replace them. Each unit collects data from its own inputs and from third-party devices (Meters API), then shares every measured value with your BMS, SCADA, DCIM, Sensdesk or other cloud platform (Open API). This means one DIN-rail unit can act as an I/O controller, a protocol gateway and a standalone alarm unit at the same time.

Data In: Modbus/RTU over RS-485

Every Perseus Industrial model has an RS-485 terminal for Modbus/RTU. Use it to read values from:

• Third-party electricity and energy meters
• UPS systems and air conditioning units with a Modbus/RTU interface
• HW Group RTU sensors for temperature, humidity and CO₂

Perseus can also read values from other devices on the LAN using SNMP, Modbus/TCP, MQTT and XML. You can then use these values in local conditions to trigger alarms or switch the DO relays.

Data Out: the Perseus Open API

All measured values, DI states and DO relay states are available through the Open API:

• SNMP (v1 and v3) and SNMP Traps: poll values into an existing NMS such as PRTG, Zabbix or SolarWinds, and send traps on alarm
• MQTT: publish data to a broker for IoT platforms
• Modbus/TCP: expose values as Modbus registers for PLCs, SCADA and BMS systems
• XML/HTTP: simple integration with custom software and scripts
• BACnet: integration with building management systems

Modbus/RTU to Modbus/TCP, MQTT or SNMP Gateway

Because Modbus/RTU comes in and Modbus/TCP, MQTT or SNMP goes out, a Perseus unit can also work as a protocol converter. For example, it can take a serial Modbus/RTU energy meter and make its readings available over the LAN to a SCADA system (Modbus/TCP), an IoT platform (MQTT) or an IT monitoring system (SNMP). No separate gateway hardware to buy.

For more information please contact our Industrial Projects Team.