The modular I/O-test platform


OCTOPUS: The modular I/O-test platform

OCTOPUS is a robust modular I / O test platform with which complex PLC installations can be tested automatically. OCTOPUS can simulate both digital and analog I / Os in parallel and has trigger functionality so that all kinds of test scenarios can be run, controlled from, for example, Python scripts, LabVIEW or MATLAB applications.

This makes OCTOPUS an ideal test platform for Engineering Regression Tests, Factory Acceptance Test (FAT) or Site Acceptance Test (SAT) environments over longer distances.

OCTOPUS is a platform that currently consists of 5 types of modules:

  • TEMSY 
    • The heart of the OCTOPUS platform. It is the interface via USB to the host PC where the test application is running and further provides power-limited power distribution, interface and synchronization of up to 100 I / O modules. In addition, with 2 trigger inputs and outputs it is possible to trigger from and to external equipment
    • The digital input module from OCTOPUS. Each TEMDI has 8 individually insulated connectors, each with 2 digital inputs
    • The digital output module from OCTOPUS. Each TEMDO has 8 individually insulated connectors, each with 3 in series connected outputs
  • TEMAIO (available 2021)
    • The combined analog input and output module. Each TEMAIO has 8 individually insulated connectors, each with 2 analog inputs and 2 analog outputs
  • TEMRTD (beschikbaar 2021)
    • A 4-wire resistor output module. Each TEMRTD has 8 individually insulated connectors, each with one 4-wire resistor output

The five modules all have a set of common properties that together form the OCTOPUS system.

OCTOPUS properties

  • Each module is “Hot swappable” due to an inrush-limiting circuit
  • Onboard temperature sensor
  • Onboard power supply monitor
  • Remotely reprogrammable via Modbus, without disassembly
  • Module status, Rx / Tx activity and IO enable indication with LEDs
  • CAT5 shielded interface connectors for power and communication
  • Communication between the modules is via the Modbus protocol over RS422 with failsafe transceivers
  • Robust against cross cabling and PoE
  • Ability to daisy-chain up to 16 modules
  • Uniquely addressable by rotary hex switches
  • Robust housing with transparent cover for direct optical feedback of LED signals and accompanying text


The TEMSY module is the heart of the OCTOPUS platform. It has multiple functions. TEMSY has a USB connector for interface with the test applications on eg a PC, laptop or Raspberry Pi. It provides inrush-limited power distribution to all module strings, and has trigger functionality to synchronize data and signals with or through other equipment. Hot swapping of module (s) is made possible due to the inrush-limiting outputs.

TEMSY properties

  • 16 connections by means of RS422 RJ45 connectors for connecting up to 100 TEMDO, TEMDI, TEMAIO and TEMRTD modules. Maximum 16 modules per connection through daisy-chaining
  • 4W4 D-SUB power connection for 24 – 48V bus voltage
  • Power supply diagnostics per connection by means of LEDs
  • Power source for the connected module strings with 16 parallel inrush limited outputs, overcurrent protected, robust against hot swapping
  • Power supply diagnostics per connection by means of LEDs
  • 2 input and 2 output trigger connections (BNC connectors)
  • Standard USB interface for reading out and controlling the connected modules
  • Central trigger distribution across all connected modules for synchronizing inputs and outputs
  • Trigger inputs are 3V3 logic compatible, ± 36V tolerant


TEMDI is the digital input module of the OCTOPUS platform. Here, digital signals from industrial systems can be monitored. With TEMDI, for example, outputs from PLCs or digital sensor outputs can be monitored / used for running test scenarios.

TEMDI properties

  • 16 digital inputs per TEMDI “soft” galvanically separated
    • Potential free inputs
    • 3V3 logic level inputs up to 24V, ± 36V tolerant
    • Minimal load to PLC outputs
  • Separate Input status indication with LEDs
  • Industrially standardized M12 connectors, pinning compatible with common PLC systems


TEMDO is the digital output module of the OCTOPUS platform. TEMDO has 8 digital outputs that can be used to control digital inputs of industrial PLC systems. With TEMDO, for example, different interlock scenarios can be simulated to handle PLC software regression tests quickly and consistently.

TEMDO properties

  • 8 digital output channels with 3 potential-free series-switched contacts
    • Qualified for redundant safety PLC inputs
    • High impedance during power-up / reset
    • Overcurrent protection from 100mA
    • ± 30V maximum differential, ± 36V single ended
    • Ability to generate closure between 2 safety PLC loops
  • Separate output status indication with LEDs
  • Industrially standardized M12 connectors, pinning compatible with common PLC systems


TEMAIO is the analog input / output module of the OCTOPUS platform. TEMAIO has an analog input front-end and an analog output module. The output voltages are directly measured back with the analog inputs to verify the output value. The TEMAIO current / voltage outputs can be used to simulate sensor current loops (4-20mA) or sensor voltage outputs (0-10V). In addition to real-time output monitoring, the analog inputs can also be used to monitor external analog voltages.

TEMAIO will be available in Q1 2021.

TEMAIO properties 

  • 16 programmable analog current or voltage outputs
    • Current range: ± 24mA, 16bit
    • Voltage range: ± 12V, 16bit
  • 16 continuous measuring analog voltage inputs
    • Input range: ± 32.8V, 16bit
  • Separate input / output status indication with LEDs
  • “Soft” galvanically separated input / output channels
  • Industrially standardized M12 connectors, pinning compatible with common PLC systems.



The TEMRTD is a resistance synthesis module in the OCTOPUS platform to simulate resistive temperature sensors. 3 ranges are defined to simulate commonly used sensor types with higher resolution and accuracy.

TEMRTD will be available in Q1 2021.

TEMRTD properties 

  • 8 programmable 4-wire resistor synthesis outputs
    • 3kΩ to 33kΩ range, <0.2%, 16bit
    • 300Ω to 3kΩ range, <0.5%, 16bit
    • 10Ω to 300Ω range, <3%, 16bit
        • 100Ω to 300Ω range, <1%
  • Autoranger can be turned on or off as required
  • “Soft” galvanically isolated output channels
  • Refresh rate of 100Hz possible
  • Input protection up to ± 24V, with peaks up to ± 33V
  • Maximum measuring current up to:
    • 400uA in the 33kΩ range
    • 4mA in the 3kΩ range
    • 15mA in the 300Ω range