The Industrial Raspberry Pi Forum

Hi, guys. We're evaluating the possibility to develope a project using Raspberry Pi now, and transplant/port/deploy developed code onto the upcoming RevPi Compact.
Basically, this project involves:
1.monitoring grinding machines
2.data acquisition from mounted sensors e.g. vibration sensor
3.some edge computing e.g. data analyzing, signal process
4.sending processed data to sever via internet or fieldbus to do troubleshooting, remaining useful life prediction etc.
5.stoping or adjusting parameters of this machine according to received instruction from sever via internet or fieldbus
It's still at a very early stage, so I wonder if I'm using standard Rasbperry Pi to develope this project now, how my code's portability and sysytem design's compatibility will be on the RevPi Compact?
For example, the current AIO module's, even upcoming RevPi Compact's, AD resolution and sample rate along with other characteristics don't really fit project's requirement. We already have a developed data acquisition solution that's verified on other project but using a dedicated stm32. We'd like to use that in this project. However, it will be rely on RPi's GPIO and serial communication ability. considering existing RevPi isn't exposing GPIO to user, can I count on RevPi Compact's IO compatibility with Raspberry Pi? Because after all we just want a robust, industrial-standard Raspberry Pi so that our design meets "the first party's" requirement.
Furthermore, how RevPi Compact's compatibility with existing DIO/Gateway/... module? We would much like to make use of these modules' brilliant industrial-standard design, both electronically and mechanically.
If convenient, a data sheet preview or anymore details would be much appreciated.

Hi, the RevPi Compacts´ data sheet is unfortunately not yet ready. The RevPi Compact has no PiBridge thus Gateway- or IO-Modules cannot be attached.
The question about GPIOs v.s. RevPi IOs is that you write to the process image and the process image is applied cyclic to IOs.
Have a look at the video tutorials:

• Quick Start Guide
• Tutorial 12 – Digital IO Modules application example

The RevPi Core Modules have two PiBridges the RevPi Connect Modules have one PiBridge and one ConBridge.
You may attach up to five (5) IO Modules on each PiBridge and you may exchange one of them with a Gateway Module. The Con Modules may be attached to the Con Bridge.
If they don't use the same periphery and the power supply is sufficient they may be used together.

Soon there will be a new Module available to the PiBridge - the MIO or Multi-IO.
Preliminary specification MIO:

4 digital GPIOs

• 24V level
• PWM output (frequency range from 2 Hz to theoretically 60 kHz)
• Pulse output (pulse length from 1ms to 65535ms)
• Discrete Out
• PWM measurement of freq and duty cycle (frequency range still has to be determined since hardware filters have not yet been set)
• Pulse measurement (pulse length from 1ms to 65535ms)
• Discrete In
• 1 x QuadEncoder

8 analog inputs

• Measuring range 0-10V
• 5.38mV resolution
• configurable as digital inputs with variable threshold voltage

8 analog outputs

• Voltage range 0-10V
• 0.33mV resolution
• configurable as digital outputs with variable switching voltage

Thanks for reply!
I'm familiar with microcontrollor and python but new to Linux/OS, so please correct me if I'm wrong.
The way I interpret how "process image" works is that IO modules are somehow electronically indepdent to Core/Connect, so you have this "process image" to communicate with modules and refresh their writing/reading value periodically. Thus they are isolated and protected well from outer environment. However, this means we can't use them as regular GPIO on RasPi nor serial communication ports.
That's a shame that IO/gateway module won't be compatible with upcoming Compact. Because the well isolated IO module and integrated Gateway module is one of the reasons we'd like to use RevPi. Now that I learned more about RevPi, I wonder if I can attach STM32 to RevPi Connect via SPI0 on the ConBridge? Or simply use the RS485 port on the front? It's still at an early stage, so any modifying recommendation is welcomed.
I'm grateful for your posting MIO features. The ADC resolution seems fairly sufficient. However, I've noticed it on another post that @lukas mentioned the max sample rate will be merely 8Hz, but we're testing a sample rate at some 20ksps. So I'm afraid MIO might not be enough for our project.

Ok I've understood that your interest comes from the microprocessor way.
Linux is fun, for me just a few commands and techniques are important on the daily doing.

Yes the process image is the hart of the data and it is just a 4Kb space in the so called Kernel space.
Have a look at the Tutorial 13 – PiTest source code to see how easy you may access it.

The IO data is refreshed periodically in real time from the picontrol driver.
So the inputs are updated to the process image and the outputs get switched accordingly.

You may attach your STM32 to the SPI of the Con Bridge, or use the RS485 on the front.
Just have a look at the schematics.

What @lukas mentioned is that the ADCs on the new RevPi Compact need 125ms per sample which leads us to 8 Hz.

Thanks！ I‘ll be looking into it

dirk wrote: Hi, the RevPi Compacts´ data sheet is unfortunately not yet ready. The RevPi Compact has no PiBridge thus Gateway- or IO-Modules cannot be attached.
The question about GPIOs v.s. RevPi IOs is that you write to the process image and the process image is applied cyclic to IOs.
Have a look at the video tutorials:

• Quick Start Guide
• Tutorial 12 – Digital IO Modules application example

The RevPi Core Modules have two PiBridges the RevPi Connect Modules have one PiBridge and one ConBridge.
You may attach up to five (5) IO Modules on each PiBridge and you may exchange one of them with a Gateway Module. The Con Modules may be attached to the Con Bridge.
If they don't use the same periphery and the power supply is sufficient they may be used together.

Soon there will be a new Module available to the PiBridge - the MIO or Multi-IO.

Preliminary specification MIO:

4 digital GPIOs

• 24V level
• PWM output (frequency range from 2 Hz to theoretically 60 kHz)
• Pulse output (pulse length from 1ms to 65535ms)
• Discrete Out
• PWM measurement of freq and duty cycle (frequency range still has to be determined since hardware filters have not yet been set)
• Pulse measurement (pulse length from 1ms to 65535ms)
• Discrete In
• 1 x QuadEncoder

8 analog inputs

• Measuring range 0-10V
• 5.38mV resolution
• configurable as digital inputs with variable threshold voltage

8 analog outputs

• Voltage range 0-10V
• 0.33mV resolution
• configurable as digital outputs with variable switching voltage

Hello dirk,

We are interested in using the revolution PI compact in our solution, however we want a controller that is expandable, and i saw that with the compact we cannot add an IO module due to the fact that the compact dosen't have a PiBridge. However, i saw on your site that we can buy a PiBridge plug, so if we buy it seperatly will it be possible to connect IO modules to the compact?

Thank you

Hi, well it is an open source system and we are here to help you making things possible. So maybe you can use the Ethernet and the RS485 interfaces together to communicate somehow. Maybe you can use the Git Hub repository to adapt all you need i.e. PiCtory for the hardware configuration. Maybe you can handle all this but does it make sense? Maybe you can talk to our sales team to sort out what you need and what options we are able to provide.