Product Description #

The RevPi Connect 4 is a 24 V industrial PC for IIoT and automation projects based on the Raspberry Pi Compute Module 4. RevPi is a basic module from the Revolution Pi product family. All devices in the Revolution Pi produt family are developed in accordance with EN 61131-2.

Components #

revpi-connect4-aufbau
Note

The components of the RevPi may vary depending on the variant.
Position Component Application

1

X2 connector RS485

RS485 Serial Interface,
Connecting the UPS

2

6 × status LED

RevPiLED

3

2 × RJ45 Ethernet

RJ45 Ethernet Interfaces,
Establishing a Network Connection

4

2 × USB A 3.2 Gen 1

USB Interfaces

5

RP-SMA[1]

WLAN and BT

6

Micro-USB

Saving and Reinstalling the Image

7

X2 connector

Relay Output,
Digital Input

8

X4 connector

Connecting the Power Supply

9

2 × locking clip

Mounting the Device on a DIN Rail

10

Ventilation Slots

Mounting the Device on a DIN Rail

11

2 × PiBridge

Connecting Expansion Modules

12

Micro HDMI

Setting up Desktop Mode

Variants #

Item No.: RAM eMMC WLAN

100376

2 GB

8 GB

–

100377

2 GB

8 GB

✔

100378

4 GB

32 GB

–

100379

4 GB

32 GB

✔

100395

8 GB

32 GB

–

100380

8 GB

32 GB

✔

For available variants see Revolution Pi Shop.

Compatibility #

The RevPi Connect 4 base module can be expanded by up to 10 expansion modules to create a Revolution Pi system:

Left side base module Right side

5 × RevPi I/O module

RevPi Connect 4

5 × RevPi I/O module

RevPi I/O Modules #

Virtual Devices #

The Virtual Devices are included as components in PiCtory:

Operating System Images #

The RevPi Connect 4 is compatible with:

Scope of Delivery #

The scope of delivery includes

  • RevPi Connect 4 (base module)

  • X4 connector

  • 2 × X2 connector

  • 2 × blind plug for PiBridge

  • Product insert

Mounting and Connecting #

The RevPi was developed for use in a control cabinet. Observe the specifications for Intended Use and all Safety Instructions.

Warning
Danger to life due to electrical shock

There is a risk of fatal electrical shock when working on devices in the switch cabinet with 230 V mains voltage.

▷ Operations in the switch cabinet may only be carried out by qualified electricians.

▷ Before carrying out any operations in the switch cabinet, switch off the power supply properly.
Caution
Damage to the device due to overheating

The ambient temperature in the switch cabinet must not exceed the maximum permissible operating temperature.

▷ Keep ventilation slots clear.

▷ Observe the installation clearances.

▷ Mount the device in the intended orientation.

▷ Do not place appliances with high input power directly next to each other.

▷ Regularly remove dust and dirt from the area around the appliance.

Carry out mounting and connecting in the following order:

  1. Mount the RevPi base module and all expansion modules on a DIN Rail.

  2. Connect all expansion modules via the PiBridge plug connector.

  3. Connect all other devices such as sensors and actuators. The interfaces available to you for this can be found in the section Components.

  4. Connect a monitor and a keyboard if you want to operate the RevPi in the desktop mode. This is not necessary if you have a network connection to access the RevPi.

  5. Finally, connect the power supply.

Connecting the UPS #

A UPS (uninterruptible power supply) ensures that devices continue to function during a fault. Depending on the type of UPS, a UPS can protect against the following faults:

  • Power failure

  • Overvoltage

  • Undervoltage

  • Frequency changes

  • Harmonics

The RevPi has a digital input, to which the status output of a UPS can be connected.

▷ Check whether your UPS is suitable for connection to the RevPi.

▷ Connect the status output of the UPS to the digital input on the X2 connector (pin IN and pin Ground (GND)).

▷ Observe the installation specifications of the UPS manufacturer.

▷ Test the UPS.

In the process image, bit 6 of the RevPiStatus variable is 0 or 1, depending on whether 0 V or 24 V is applied to the input. Your application must read this bit cyclically. If the UPS reports a problem, your application must initiate a corresponding measure. What exactly should be done depends on:

  • the size of the battery used,

  • the current consumption of the RevPi,

  • the current consumption of all components that are additionally connected to the UPS.

Typically, the system is brought into a safe state and the RevPi is shut down.

Access to the Device #

The RevPi is accessed in two steps:

  1. Establishing a Network Connection.

  2. Login on the device.

Install all available updates as soon as the RevPi is connected to the internet. This ensures that the system is always up to date with security-relevant features.

See also:

Alternatively, access is possible without a network, see Setting up Desktop Mode.

Configuration #

The RevPi is configured in two steps:

  1. As of RevPi Bookworm (10/2024) you configure the RevPi base module via the application Cockpit.

  2. You configure the Revolution Pi system, i.e. a RevPi base module with expansion modules, using the application PiCtory or, if applicable, directly in your development environment, e.g. via CODESYS.

Note

CODESYS and PiCtory cannot be used in parallel for configuration. An existing configuration via PiCtory will be overwritten by a configuration via CODESYS.

The virtual devices OPC UA Server and MQTT Client can only be used via PiCtory.
Note

Until RevPi Bullseye (04/2024), the RevPi base module is configured via the RevPi Status application.

Parameterization #

The following parameters, inputs (INP) and outputs (OUT) can be configured:

RevPiStatus (INP) #

Uses bits to represent different states of the piControl driver.

Bit Function

0

piControl driver is running.

1

At least one connected I/O module has not been configured.

2

At least one I/O module has been configured but not connected.

3

An I/O module occupies more or fewer bytes in the process image than specified in the configuration.
This means that the version of the configuration file or the device description files used does not match the firmware in the I/O module.
See also: Update firmware.

4

Without function.

5

Without function.

6

Digital input on X2 connector

RevPiIOCycle (INP) #

Displays the cycle time of the PiBridge communication between the base module and expansion modules in milliseconds (ms) as an integer value.

RS485ErrorCnt (INP) #

Counts the errors in the communication with the RevPi I/O modules and outputs their number as an integer value.

Core_Temperature (INP) #

Displays the CPU temperature as an integer value in degrees Celsius (°C).

Core_Frequency (INP) #

Displays the CPU frequency in MHz / 10, e.g. 2400 MHz = value 240.

RS485ErrorLimit1 (OUT) and RS485ErrorLimit2 (OUT) #

RS485ErrorLimit1 and RS485ErrorLimit2 serve as threshold values for error handling in the communication between the RevPi device and the I/O modules.

At the end of each communication cycle, the error counter RS485ErrorCnt is compared with these two limit values:

  • RS485ErrorLimit1: When this value is reached, a message is generated in the log file kern.log. In future piControl versions, the default values defined in PiCtory will also be written to the process image.

  • RS485ErrorLimit2: If the error counter reaches this value, PiBridge communication is terminated completely.

Note

The communication via the serial interface RS485 to the outside is not affected, only the internal PiBridge data traffic.

The respective check is deactivated by setting the corresponding value to 0. If, for example, RS485ErrorLimit1 is set to 0, no warning messages are generated in kern.log.

The default values are:

  • RS485ErrorLimit1: 10

  • RS485ErrorLimit2: 1000

These values offer a good balance between fault tolerance and system stability for most applications.

RevPiLED (OUT) #

The freely programmable LEDs can be controlled via RevPiLED, see Configuring LEDs.

Bit Component Status information

2:0
5:3
8:6
11:9
15:12

LED A1
LED A2
LED A3
LED A4
LED A5

000 = off
001 = red
010 = green
100 = blue
011 = orange
110 = cyan
101 = magenta
111 = white

RevPiOutput (OUT) #

The relay contact is controlled via RevPiOutput, bit 0.

RS485 Serial Interface #

revpi-connect-4-rs485-pinout

The RevPi has an RS485 interface on the upper X2 connector to connect serial devices such as sensors.

The socket has differential data line terminals P/N and reference terminals (internal GND and functional earth via 1 MOhm RC network).

Under Linux, the interface can be addressed via the device driver node with /dev/ttyRS485 .

How you use this connection optimally depends on your project environment. The network you are working with or the EMC load are individual factors that influence how you assign this connector.

We therefore cannot show you the best solution for your individual project, but we have compiled a list of the problems that can occur and tips on how you can solve them.

RS485 is a fully differential line and does not normally require a third GND line. However, due to the limits of the input receivers (maximum common mode voltage), there may be problems with the signal quality if no potential reference is used between the transmitter and receiver. However, connecting the internal GND to a line that is subject to EMC can lead to EMC problems within the RevPi Connect.

We therefore recommend that you use a common functional earth between all RS485 network participants. This gives you a good, common reference potential for the differential bus signal.

If this does not work either, you can connect the FE terminal of the RS485 connector to the third (GND) line of the bus.

You can also try to solve signal problems with the GND terminal.

Activating Termination Resistor

✓ The integrated 120 Ω terminating resistor of the RS485 interface is switched off after a restart.

▷ Log in to the RevPi via a terminal.

▷ Check out the Git repository of the command line tool rs485_config from GitLab with the command:

git clone https://gitlab.com/revolutionpi/rs485_config.git

▷ Build the tool with the command:

cd rs485_config; make

▷ Activate the resistor with the command:

./rs485_config <SERDEV> --set-bus-term

Replace <SERDEV> with the name of the interface, e.g. /dev/ttyRS485.

▷ Check whether the resistor has been activated and display the settings of the RS485 interface with the command:

./rs485_config <SERDEV>

❯❯ If the resistor is activated, Bus termination: Yes is output.

RJ45 Ethernet Interfaces #

The RevPi can be connected to a network via the RJ45 interface.

10/100 Ethernet connections are available on the RevPi, which are independent of each other. This allows the RevPi to be integrated into two different networks. The MAC addresses are printed on the front of the housing. Under Linux, the interfaces can be addressed with:

  • Socket A: eth0

  • Socket B: eth1

WLAN and BT #

WLAN Interface

✓ RevPi base module with WLAN interface

✓ DHCP-enabled WLAN router

▷ Use ip link to check whether a Wi-Fi interface is available.
In Linux, the Wi-Fi interface is displayed as wlan0, provided that no other Wi-Fi device is available.

▷ Activate the WLAN interface via Cockpit[2].

▷ Set up the WLAN connection via NetworkManager.

BT Interface

A BT interface[3] is available from standard 5.0.
▷ Activate BT via Cockpit in order to connect Bluetooth peripheral devices such as keyboards or audio devices to the RevPi.

See also:

USB Interfaces #

The RevPi has two USB A 3.2 Gen 1 interfaces. The maximum output current per USB interface is 800 mA and is only guaranteed if the RevPi is supplied with 24 V DC -15 % / 20 %.

In the event of an overload, the power is switched off at the corresponding USB interface.

Relay Output #

The RevPi has a relay output on the lower X2 connector.

This relay output can be used, for example, to interrupt the power supply to connected hardware.

  • The relay can switch a maximum of 30 V and 300 mA.

  • The relay contact is open after the start.

▷ Make sure that all devices are disconnected from their power supplies.

▷ Connect the load to be switched to the OUT pins on the X2 connector.

▷ Connect the power supply.

The relay output is controlled in the process image via the status byte RevPiOutput, bit 0.

Digital Input #

The RevPi has a digital input for a +24 V input signal on the lower X2 connector.

The input has an internal pull-down resistor.

The digital input can be used to connect a UPS.

▷ Make sure that all devices are disconnected from their power supplies.

▷ Connect the signal transmitter to the IN+ and IN- pins of the X2 connector.

▷ Connect the power supply.

Trusted Platform Module (TPM) #

The RevPi is equipped with an Infineon OPTIGA™ TPM SLB 9670 Trusted Platform Module. It fulfills the requirements of TPM 2.0.

Under Linux you can address the module with /dev/tpm0.

Watchdog #

A watchdog is a timer that restarts the RevPi after 60 seconds. To prevent this from happening, the watchdog must be reset regularly as long as the system is running without errors. In the event of an error, such as a crash of the application process, there is no reset and the watchdog triggers a restart of the RevPi.

The RevPi has two independent watchdogs. There are various ways to use a watchdog under Linux. Revolution Pi and Raspbian Pi use the system manager systemd.

Integrated Watchdog

The watchdog integrated on the processor behaves like other watchdogs under Linux and can be addressed with:

  • /dev/watchdog0

  • /dev/watchdog (as standard watchdog)

External Watchdog

A second watchdog is available via the RTC module and can be addressed under Linux with:

  • /dev/watchdog1

See also:

Technical Data #

Item No.: 100376, 100377, 100378, 100379, 100395, 100380

Housing dimensions (H × W × D)

96 × 45 × 110.5 mm

Housing type

DIN rail housing for TH35 according toDIN EN 60715

Housing material

Polycarbonate

Weight

Approx. 197 g / 224 g (incl. connectors)

Protection class

IP20

Power supply

10.8 … 28.8 V DC[4]

Maximum power consumption

20 W (incl. 2 × 800 mA USB load)[5]

Approved operating temperature

-25 … +55 °C

Approved storage temperature

-40 … +85 °C

Max. relative humidity (at 40 °C)

93 % (non-condensing)

Interfaces

  • 2 × USB A 3.2 Gen 1

  • 2 × RJ45 Gbit Ethernet

  • 1 × RS485 screw-type terminal

  • 1 × Micro-USB (solely for image transfer to eMMC)

  • 1 × Micro-HDMI 2.0a (4K)

  • 2 × PiBridge (connectors at left and right side)

  • 1 × RP-SMA socket for WLAN 2.4/5 GHz, BLE 5.0 (Item No.: 100377, 100379, 100380)

Connectors

  • 1 × 4-pole screw-type terminal for RS485

  • 1 × 4-pole screw-type terminal for relay contact and signal input

  • 1 × 4-pole screw-type terminal for power supply

Processor

Broadcom BCM2711, quad-core Arm Cortex-A72

Clock rate

1.5 GHz

Processor cooling

Passive with heat sink

RAM

2 GB LPDDR4 (Item No.: 100376, 100377), 4 GB LPDDR4 (Item No.: 100378, 100379), 8 GB LPDDR4 (Item No.: 100395, 100380)

Flash memory

8 GB (Item No.: 100376, 100377), 32 GB (Item No.: 100378, 100379, 100395, 100380)

Trusted Platform Module

TPM 2.0 Infineon OPTIGA™ TPM SLB 9670

WLAN / BT

2.4 GHz, 5.0 GHz IEEE 802.11 b/g/n/ac wireless; BT 5.0, BLE (Item No.: 100377, 100379, 100380)

Number of digital inputs

1

Digital input type

24 V DC control voltage (e.g. for power-good signal of a UPS)

Input threshold

Approx. 10 V DC (0 → 1) or 7 V DC (1 → 0); input current 2.4 mA (according to IEC 61131-2)

Number of digital outputs

1

Output type

Opto-decoupled solid state relay, normally open, max. 30 V, 300 mA DC, any polarity

Software interface of input and output

Via GPIOs and process image

Hardware watchdog

Watchdog in RTC device, freely configurable watchdog character device

Compatible RevPi modules

  • All RevPi I/O modules can be connected via the PiBridge system bus.

  • Up to 5 modules can be connected to the left and right side of the device.

EMC interference emission

According to IEC 61000-6-4 (emission standard for industrial environments)

EMC immunity

According to IEC 61000-6-2 (immunity standard for industrial environments)

Mean time between failures (MTBF) at 25 °C

30.7 years

Mean time between failures (MTBF) at 50 °C

20.5 years

RTC buffer

CR2032 lithium battery, lifetime approx. 10 years

Optical display

6 status LEDs;
5 × red/green/blue (freely programmable), 1 × red/green

Conformity

CE, UKCA

UL certification

UL File No. E494534
NOTE: The device may only be supplied from circuits that comply with Class 2 or Safety Extra Low Voltage (SELV) according to Class 9.4 of UL 61010-1.
1. only for the variants with WLAN
2. Up to RevPi Bullseye, WLAN is activated via RevPi Status.
3. Up to RevPi Bullseye, BT in the terminal via the HCI interface activated
4. The bridging time required by EN 61131-2 for voltage dips of at least 10 ms and the maximum USB output current are only guaranteed with a supply voltage of 24 V DC -15 % / +20 %.
5. The average power consumption without USB load varies greatly and depends on the use of the interfaces, GPU, and CPU. It is usually well below 4 W without HDMI.