Raspberry Pi Family Products

——Revolutionary Now

Industry 4.0, Don’t Just Raise Requirements—Make It Happen!

During the launch of the Revolution Pi product, KUNBUS introduced an open, modular, and cost-effective industrial PC based on Raspberry Pi, equipped with Raspberry Pi compute modules. The base module can be seamlessly expanded with appropriate I/O modules and fieldbus gateways as needed. The IPC developed by KUNBUS based on the Raspberry Pi compute module consists of open hardware and software, complying with EN61131-2 standards. Due to its modular structure, Revolution Pi can connect to industrial networks through digital or analog I/O modules and corresponding fieldbus gateways as per customer requirements. Installed in a DIN rail enclosure, the base module of Revolution Pi already has USB, Ethernet, and HDMI connectivity, with modules and expansion modules powered by standard industrial 24V supply.

To showcase circuit diagrams, KUNBUS strictly pursues the concept of open-source software, pre-installing the Raspbian operating system built from Raspberry Pi, which includes pre-installed expansion module drivers. Essentially, all software or programs can run on Raspberry Pi and also on Revolution Pi, with full access for root operations, programming, and executing custom programs. By collaborating with various software manufacturers, KUNBUS provides customers with preferred, cost-effective, powerful control and SCADA software, thus allowing Revolution Pi to evolve into a small, industrially viable control system.

On online forums, Revolution Pi developers and users from around the world can exchange questions, solutions, and improvement suggestions more quickly, openly, and easily.

Why Raspberry Pi?

Raspberry Pi Compute Module 1, 3, 3+

Since its launch in early 2012, Raspberry Pi has had an impressive product life. By mid-2019, over 25 million units of the small, inexpensive single-board computer had been sold. The idea behind the development of Raspberry Pi is to produce cheap and simple PCs that can also guide children into the world of programming. Although most Raspberry Pis are currently more suitable for home media centers, they are increasingly being used for environmental testing and industrial laboratories.

Various versions of Raspberry Pi have become popular, and we at Kunbus prefer to use the lesser-known term compute module. Why? Simply because using the term compute module limits Raspberry Pi to more important fields, allowing us enough room to design its connections in an industrially viable manner. Currently, there are two versions of the compute module, one with a single-core processor and the other with a quad-core processor.

Revolution Pi—More Than Just a Device

Revolution Pi is not just a device for us. We believe it is time to break the inherent structures in the industry with the open-source concept. We will openly showcase our source code and all circuit diagrams belonging to the Revolution Pi devices. Our customers should not be limited to our ideas and solutions. This can allow you to unleash your creativity. If these ideas are then freely exchanged with other users on the Revolution Pi platform, a powerful community will develop. We will provide tools for such networking through Facebook, video channels, forums, and blogs. In the future, there will be an application store where you can search for solutions or provide them yourself. Together, we can make outstanding contributions to the challenges of Industry 4.0.

No Secrets—The Circuit Diagram of the Base Module is Publicly Disclosed

Base Module—The Foundation of Revolution Products

RevPi Connect, RevPi Core 3, and RevPi Core are the central processing units of our modular system. By using Raspberry Pi Compute modules, these devices are largely compatible with Raspberry Pi Module 3 or Raspberry Pi B+.

A very important element of our Revolution Pi base module is its power supply unit. To ensure thermal losses are kept to a minimum, we use state-of-the-art, highly efficient DC-DC converters (total efficiency >80%), with standard 24V as the necessary operating voltage reference in the process switch cabinet.

However, our core modules operate not only within the standard power supply range of 20.4V to 28.8V but also at an input voltage of 10.7V. This means you can even use a car battery or solar panel as a power source. Under 24V power, RevPi Core can withstand a voltage drop of 10ms without interruption (USB sockets fully loaded), and even 25ms when USB sockets are unloaded. The power supply voltage and functional ground are connected using very robust connectors from below.

Precision protection circuits ensure uninterrupted operation, even in environments where there is significant electrical or electromagnetic interference on the input power line (as long as the functional ground is connected). Lightning strikes or nearby welding interference have been simulated in our test lab and do not interfere with our RevPi core modules.

RevPi Core is equipped with two USB-A connectors located at the front, which can be used for USB2.0 client devices. Both connectors can drive a maximum of 500mA on their 5V power pins. Therefore, you can easily connect USB drives or surfsticks directly without an active USB hub. The intermediate micro USB socket is used to connect to the USB host system (usually a PC) and switch RevPi Core to passive storage card mode. In this way, for example, the PC can access the installed eMMC flash memory and store software there.

LAN ports can be connected via RJ45 Ethernet. Alternatively, a WLAN-USB dongle can establish a connection to LAN. USB and Ethernet connections have suppression circuits for radiation or ESD and do not damage the Revolution Pi system.

The Broadcom processor of the compute module provides high-resolution graphics capabilities. Therefore, the RevPi base module is equipped with a micro HDMI socket on top for connecting displays with audio output. Thus, a fully equipped PC can be used with a mouse and keyboard.

The Pi Bridge is the high-speed data channel connecting the various modules of Revolution Pi. The two adjacent modules on the top of the enclosure are interconnected via a system connector.

Revolution Pi comes with Raspbian as the default operating system (a Debian variant) and a real-time patch for the kernel. For more information on software, drivers, etc., please see below.

RevPi Connect—For Users Needing More Interfaces

RevPi Connect pays tribute to those who wish to use the Revolution Pi system as an IIoT gateway. Therefore, the base module offers more interfaces. Like RevPi Core 3, RevPi Connect is equipped with Raspberry Pi Compute Module 3.

Two Ethernet interfaces allow the device to be integrated simultaneously into automation and IT networks, for example, transferring machine data from the workshop to the cloud or higher IT systems.

The hardware monitor allows RevPi Connect to be used anywhere, even in hard-to-access areas. The hardware watchdog monitors the status of RevPi Connect, i.e., relay outputs to ensure separate monitoring or resetting of connected devices or extensions on the module. RevPi also has a 24V input to receive UPS shutdown signals.

Unlike RevPi Core 3 or RevPi Core, RevPi Connect does not have two PiBridge connectors mounted on top; instead, each has one PiBridge and one ConBridge connector. While PiBridge is responsible for connecting various IO expansion modules and fieldbus gateways, ConBridge can connect CAN bus and M-Bus extension modules. In the future, different radio standards will be further expanded and can be connected via ConBridge.

The front of RevPi Connect also has a 4-pin RS-485 interface, for example, for connecting Modbus sensors.

45mm, RevPi Connect is twice the width of RevPi Core 3

Base Module—Actual Parameters

RevPi Connect+	RevPi Connect	RevPi Core 3+	RevPi Core 3	RevPi Core
Processor	BCM2837B0	BCM2837	BCM2837B0	BCM2837	BCM2835
Number of Cores	4	4	4	4	1
Clock Frequency	1200MHZ	1200MHZ	1200MHZ	1200MHZ	1200MHZ
RAM	1GB	1GB	1GB	1GB	500MB
eMMC Flash	8/16/32GB	4GB	8/16/32GB	4GB	4GB
Power Supply	12-24V	12-24V	12-24V	12-24V	12-24V
Dimensions (L*W*H)	111*45*96mm	111*45*96mm	111*22.5*96mm	111*22.5*96mm	111*22.5*96mm
Operating Temperature	-40~+55℃	-40~+55℃	-40~+55℃	-40~+55℃	-40~+55℃
Storage Temperature	-40~+85℃	-40~+85℃	-40~+85℃	-40~+85℃	-40~+85℃
Humidity	93%, no condensation	93%, no condensation	93%, no condensation	93%, no condensation	93%, no condensation
Protection Level	IP20	IP20	IP20	IP20	IP20
ESD Protection	4KV/8KV	4KV/8KV	4KV/8KV	4KV/8KV	4KV/8KV
EMI Testing	Passed	Passed	Passed	Passed	Passed
Surge Testing	Passed	Passed	Passed	Passed	Passed
CE	Yes	Yes	Yes	Yes	Yes
RoHS	Yes	Yes	Yes	Yes	Yes
Operating System	Custom Raspbian	Custom Raspbian	Custom Raspbian	Custom Raspbian	Custom Raspbian

Interfaces (Quantity)

RevPi Connect+/Connect	RevPi Core 3+/Core 3	RevPi Core
RJ45 Ethernet Port (10/100Mb/s)	2	1	1
USB 2.0 Interface	2	2	2
Micro HDMI Interface	1	1	1
Micro USB 2.0 Interface (Firmware Upgrade)	1	1	1
RS485 Terminal (4-wire)	1	–	–
PiBridge (Expansion Module)	1	2	2
ConBridge (Expansion Module)	1	–	–
24V Input for UPS Shutdown Signal	1	–	–
Freely Programmable Relay Switch Contacts	1	–	–

Available Expansion Modules

Name	Function	Article Number	RevPi Connect+/Connect	RevPi Core 3+/Core 3	RevPi Core
RevPi DIO	Digital IO Module	100197	*	*	*
RevPi DI	Digital Input Module	100195	*	*	*
RevPi DO	Digital Output Module	100196	*	*	*
RevPi AIO	Analog IO Module	100250	*	*	*
RevPi Gate PROFINET IRT	PROFINET IRT Device Gateway/Slave	100074	*	*	*
RevPi Gate PROFIBUS	PROFIBUS Slave Gateway	100069	*	*	*
RevPi Gate EtherNet/IP	Ethernet/IP Adapter Gateway/Slave	100066	*	*	*
RevPi Gate DeviceNet	DeviceNet Adapter Gateway/Slave	100071	*	*	*
RevPi Gate EtherCAT	EtherCAT Slave Gateway	100073	*	*	*
RevPi Gate POWERLINK	POWERLINK CN Gateway/Slave	100076	*	*	*
RevPi Gate SERCOS III	SERCOS III Slave Gateway	100075	*	*	*
RevPi Gate Modbus TCP	Modbus TCP Slave Gateway	100088	*	*	*
RevPi Gate Modbus RTU	Modbus RTU Slave Gateway	100090	*	*	*
RevPi Gate CANopen	CANopen Slave Gateway	100070	*	*	*
RevPi Gate DMX	DMX Master/Slave Gateway	100237	*	*	*
RevPi Gate Serial	Serial Slave Gateway	100068	*	*	*
RevPi Con M-Bus	Wireless M-Bus Module (868MHz)	100281	*	–	–
RevPi Con M-Bus VHP	Wireless M-Bus Module (169MHz)	100282	*	–	–
RevPi Con CAN	CAN Bus Module	100286	*	–	–

Digital IO module RevPi DIO with 14 inputs and outputs

Digital I/O Modules

To transform Revolution Pi into an industrial control unit, various digital I/O modules and other components can be connected to the basic RevPi core module.

The I/O modules are released in three versions, all having the same 28-pin I/O pins (connectors, with two rows of 14 pins each—two appropriate 14-pin socket connectors with spring clip contacts for connecting twisted wires up to 1.5mm²), in addition to the standard 14-pin digital input and 14-pin data output, there are also two special versions with separate 16 digital inputs or 16 digital outputs. In all three versions, inputs and outputs are high voltage isolated (due to the PI Bridge) with isolation voltage up to 600V. The standard version also has output high voltage isolation, and all versions have interference protection, capable of operating in -40~50 degrees Celsius environment and up to 80% relative humidity, the standard version module also comes with PWM output (pulse modulation) and counter input.

In the loop data transmission time between the RevPi core module and I/O modules, we obtained the following test results based on system configuration: with one I/O module and two gateway modules: guaranteed 5ms cycle time; with three I/O modules and two gateway modules: guaranteed 10ms cycle time, which only applies if the task scheduling table on the operating system is correctly prioritized.

According to EN61131-2 standards, for type 1 and type 3, inputs operate on 24V power supply with switching thresholds. The input current limit is a maximum of 2.4mA per input. At 12V power supply, this standard no longer applies, and if the power supply voltage is interrupted and drops below 9V, an alarm will be automatically sent to RevPi Core indicating that the transmitted input value no longer meets the reliable threshold defined by the 24V switching logic in the standard. An adjustable low-pass filter can be used to debounce input signals. It can only be turned on for all inputs at the same time. If the input is stable for at least 25μs, 750μs, or 3ms, the filter only passes input changes. The filter can also be completely turned off. According to EN61131-2 requirements, inputs are protected against electrostatic discharge, burst pulses, and surge pulses.

Each output can be individually configured as a high-side switch with a load capacity of up to 500mA or as a push-pull output with at least 100mA load capacity. All outputs have short-circuit protection, regardless of the operating mode. The watchdog circuit ensures that outputs are set to 0 (safe state) once the STM processor stops transmitting any data to the output from the Pi Bridge. In the event of undervoltage at the output power connection or overheating, the output is also set to 0. These last two error states and short-circuit fuses for each channel are transmitted to RevPi Core via the Pi Bridge.

Additionally, outputs can be configured to enable open-load detection (line disconnection) and send corresponding alarms to the high-end output type RevPi Core. Like the inputs, outputs can also be protected against electrostatic discharge, burst pulses, and surge pulses according to EN61131-2 requirements.

RevPi Gates are suitable for all common industrial network protocols, helping to integrate Revolution Pi into industrial networks

Connecting Fieldbuses

Integrating devices into industrial networks is not easy. Special protocols are often used for data transmission, such as Profinet or Profibus. When using our gateways—referred to as RevPi gateways, integrating Revolution Pi into industrial networks is not an issue.

Like all Revolution Pi expansion modules, gateways are connected to the base module RevPi Core via the pin PiBridge connector. Therefore, each system can use up to two gateway modules. These, like all modules, provide 24 volts, which is the industry standard. We currently set the cycle time between RevPi Core and the gateways to 5ms through drivers. While gateway modules can achieve cycle times of less than 2ms, they would impose an inappropriate load on the RevPi Core system. The shorter the cycle time set in the drivers, the greater the system load on RevPi Core, which must consume for that process. The gateways for our current network protocols are as follows. All different protocol modules have been tested and confirmed in the corresponding user organizations:

Analog IO Modules

Using analog IO module RevPi AIO expands Revolution Pi. You can not only expand the system with 4 analog inputs and 2 analog outputs but also with 2 RTD inputs.

The 2 RTD inputs can measure temperature in a high precision range from -165℃ to +600℃ every 0.5℃ using common RTD sensors, such as Pt100/Pt1000 probes. The probes can be directly connected to the module via 2, 3, or 4 wire cables.

Inputs, RTD inputs, and outputs are electrically isolated from each other. Differential inputs eliminate ground loops.

RevPi AIO expansion module connects to the RevPi base module via the top-mounted PiBridge plug.

Like the digital IO modules, RevPi AIO can prevent interference according to EN61131-2 and can operate in an environment temperature of -40 to +50℃ and up to 80% relative humidity. According to EN61131-2 requirements, it can also prevent electrostatic discharge, bursts, and surge impacts.

RevPi Core 3 and RevPi AIO on DIN Rail

Open Source Also Needs Software

Revolution Pi is an open platform where everything can be installed to run on Raspberry Pi, from the operating system to applications.

We decided to pre-install Raspbian (a Debian variant) with Wheezy version RT patch 4.1.13 kernel. In our view, it is the best compromise to keep the original development environment of Raspberry Pi as close as possible while still maintaining high control over task scheduling priorities. The modified kernel can be widely configured to control the operating system’s task scheduler to ensure avoiding delays typically caused by network access and other I/O access operations. Appropriate drivers have obviously been pre-installed for the expansion modules.

On this basis, you can purchase soft PLC logi.cals and SCADA software PROCON-WEB IoT or other software from our online store. These components allow you to have a complete and operational PLC.

But perhaps you also want to write your own software under Linux using Python? Then you can access all process data using our drivers and optimized operating system version. For this, we store a process image with all current process values that can be easily written or read in the memory area.

Simple Configuration with PiCtory

Each Revolution Pi system comes with PiCtory configuration software. It allows you to define the positioning of hardware modules and the symbolic names of input and output signals. Additionally, PiCtory can also be used to configure connected hardware modules or installed drivers.

Revolution Pi is an advanced, modular, and scalable system. For example, you can write your own drivers to seamlessly integrate your special hardware into the system. The central process image in memory is the link between all components. Components, whether hardware modules or software applications, always exchange data with this process image. But in doing so, the driver must also know precisely where (at which address in memory) to find the individual process values.

PiCtory is a browser application. The server is pre-installed on our RevPi Core. Alternatively, you can also use a PC program (Windows) with a small web server installed.

You can arrange the desired system through drag and drop. Predefined rules help you position modules correctly. Automatic detection prevents unavailable combinations. In addition to the expansion modules we provide, you can also add your own modules to the configuration tool.

When defining, for example, all I/O signals, PiCtory also supports you. You can assign symbolic names and define the adapter for providing and retrieving data. The adapter can be a hardware module on PiBridge, but it can also be a “virtual device”—for example, driver software where memory locations are retained in the process image and process values can be defined with symbolic names. The completed configuration file is stored as a JSON file and transmitted to RevPi Core.

PiCtory can help you set up the Revolution Pi system

Software Special Edition

Revolution Pi is a very flexible solution because we offer various software that can be used on the Revolution Pi hardware series. If you need IoT tools or PLC software—just choose the software that suits your needs. Below is a list of applications already available (additional licensing costs may apply):

CODESYS

Manufacturer-independent IEC 61131-3 automation software for planning control systems, turning Revolution Pi into a small industrial controller. Thanks to the built-in soft master station functionality for various industrial protocols, Revolution Pi systems can be integrated into industrial networks without the need for gateway modules.

Modbus TCP & Modbus RTU

Fully available through PiCtory functionality, Modbus master and slave can exchange data with the process image cycle, thus allowing data exchange with all other SW components. The destination and interval for communication with Modbus protocol can be freely configured. This means that, together with RevPi Gate, there is an additional low-cost way to connect multiple sensors, actuators, and controllers to the Revolution Pi device.

KUNBUS Cloud

KUNBUS Cloud supports traditional IoT data pools as a cloud service. The software agent installed on Revolution Pi ensures the highest level of security while remaining user-friendly. Each device can be individually configured to determine which data should be aggregated and at what intervals. It can also be configured via the Internet. KUNBUS Cloud can be booked as a service or installed on the customer’s server.

Node-RED

Using the open-source software Node-RED, users can quickly and effortlessly map (IoT) applications using a browser-based programming tool. In addition to control tasks, Node-RED can also be used to create browser-based HMIs.

PROCON-WEB IoT

PROCON-WEB IoT is a highly specialized HMI software that displays data in the process image through a browser-based interface. In the opposite direction, data can also be written to the process image through the browser, for example, to remotely adjust setpoints. Since PROCON-WEB IoT runtime can run on the RevPi web server, data can be securely accessed from the Internet using the new TeamViewer Client. The related PROCON-WEB IoT DESIGNER is a highly flexible editor that runs on Windows PC.

TeamViewer

By activating the software agent at startup, TeamViewer users can now also access and remotely control their Revolution Pi devices via the Internet. Using the very secure and user-friendly TeamViewer technology, RevPi web server can be accessed through a browser window. Thus, all functions can be handled through the server and provided by the browser.

logi.CAD 3

logi.CAD 3 is engineering software for creating control applications for Revolution Pi that comply with IEC 61131-3 standards. The special adjustments for the Logi RTS operating system for Revolution Pi transform the device into an SPS mini-controller suitable for industrial applications.

RevPi7

RevPi7 is the S7 software interface running on our Revolution Pi, which can be used with all S7 devices with PN connections. It consists of virtual master and slave modules that can be configured by PiCtory. The RevPi7 master provides up to 64 bytes of input, output, and tags, which are located in the process image of RevPi and can be written or read by any S7 HMI through PN connectors. The RevPi7 slave can be configured for cyclic tasks to poll or write data from the S7 PLC into RevPi’s process image via PN. Of course, this is not a substitute for Profinet or Profibus gateways—it’s much slower (task cycle time starts at 100 milliseconds). However, for gateway solutions, there is no need to change anything in your PLC software. Just activate HMI access to all inputs, outputs, tags, or DBs you want to read or write. That’s all!