I'm planning on building a cluster of 5 or more rpi4b (v1.1).
Tutorial for that: Build a Raspberry Pi Cluster Computer
All is fine and dandy except for the power supply for all the units.
I have no intention of having individual cords from each unit to the wall, so I thought of a USB hub power supply with multiple ports. This would also allow me to increase the unit count in the future will less hassle.
Also, assume an ethernet cable and a small SSD drive connected via USB per unit. No screen or HID device connected.
What would be a good fit for running the cluster 24/7?
I thought of these:
IWAIVON USB Wall Charger
Anker PowerPort Speed 4 Port
Anker PowerPort 10
RavPower Prime 60W 6 Port
Assuming that every USB port in the hub will be (eventually) connected and having in mind that RaspberryPi4B v1.1 specs states that it requires a 5v/3A power supply which none of these supply, what will be a good USB hub power supply? It doesn't have to be one I listed...
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I am currently working on a project that involves communication between a PLC , Raspberry Pi 4 and a BMS (Battery Management System) system on a battery.All three device use RS485 for communication using minimalmodbus via python on the RPI.
The Raspberry pi has a generic CAN/RS485 HAT (similar to this : https://www.waveshare.com/rs485-can-hat.htm)
Currently I am able to communicate with the PLC to receive and send data from the RPI with the PLC as a master and the RPI as a slave.
As per my understanding , in order to read data from the BMS using the Pi, the RPI has to be a master. But in this case, as the RPI is a slave to the PLC, and the PLC cannot be used to read data from the BMS.
I would like to know if it is possible for the RPI to function as a Master to the BMS when being a Slave to the PLC at the same time ?
Assuming that it is possible able to connect another RS 485 HAT to the same RPI and run separate scripts for each HAT.
I'm working on a project where I need two raspberry pis to communicate and the ethernet port is not free, I'm not allowed to make any changes to the GPIO pins, and I'm forced to use the USB port due to hardware considerations. Is it possible for them to communicate using a direct USB cable, or perhaps using two USB-RS232 cables?
Thanks!
Siddharth
I would use the TTL serial pins on the GIO header. See https://elinux.org/images/1/13/Adafruit-connection.jpg
You could create your own simple null modem serial cable - consisting of 3 jumper cables.
Connect pins
6 <--> 6
8 <--> 10
10 <--> 8
If you can't use the GPIO header - you can do a USB to USB connection using USBNET. http://www.linux-usb.org/usbnet/
Is it possible for them to communicate using a direct USB cable, or perhaps using two USB-RS232 cables?
You fail to mention exactly which Raspberry Pi version(s) you are using.
Only the Raspberry PI Zero can be used as a USB Gadget.
Since USB is a master-slave(s) interface & protocol, you cannot simply connect two Raspberry PI 1/2/3 boards together using USB, because that would be a master-to-master connection.
If you look hard enough for a (passive) USB Type A (male) to Type A (male) cable, you can find them, but it's a bogus connection that will not work.
There are active USB host-to-host cables (which contain a shared gadget), but support can be an issue.
You could connect a Raspberry PI 1/2/3 to a Raspberry PI Zero by USB, so long as the Zero's USB port was configured as a USB ACM CDC gadget.
However one simple solution is your alternative of installing USB-to-RS232 adapters to each board. A null-modem cable of three wires would suffice unless you needed hardware flow-control.
An alternative solution is installing USB-to-Ethernet adapters to each board (with static IP addresses, i.e. an ad-hoc connection). This approach provides a much faster connection than an RS-232 link, and is easily utilized by applications.
I wanna catch probe requests of mobile devices that are not connected to a network using monitor mode on Raspberry pi 3. I am using Raspbian OS. I used "Wifite" command but it only shows the mac addresses of access points and not of the non connected mobile device. I am a beginner in networking and Raspberry pi. Kindly guide me which commands should I use for this purpose?
You might try looking into sniff-probes.
It switches WiFi channels every two seconds and captures incoming packets using tcpdump.
I'm just bought a new Raspberry Pi 3 (and also 5V,2.5A Power Supply). And I'm totally a fresher to this so before to start using it I have some few question about its power.
I'm now connect my Pi with:
1. 1 Screen Monitor (Powered with another Power Supply) connecting through HDMI.
2. 1 Keyboard (USB port).
3. 1 Mouse (USB port).
4. 1 External Drive WD My Passport Ultra (with 3.0 USB cable) (USB port).
My question is does my Pi have enough power to handle all this above mentioned devices and if it is, can I use one more USB port for another device such as WD Passport and GPIO for a radiator fan ?.
Thank you for all your helps.
When your Pi will have not enough power for all peripherals you will see small yellow flash on screen. Then you should upgrade your power supply.
We have a shared PC in our LAB, connected to a Vector Network Analyzer (VNA). The PC communicates with the VNA through GPIB port, using Matlab functions. For my work, i need to acquire real-time data from the VNA into my own PC, which is few meters away from the VNA PC. I dont want to have wireless solutions due to the interference that might happen. I intend to buy a USB data transfer cable to connect the Matlab. But i couldn't find in google any similar idea to do so. I was wondering is such a solution practical? Does anybody has the same experience? And will be any problem regarding the drivers?
in USB bus systems there can only be one USB host all other devices are in USB device mode.in most cases the USB controllers of PCs are not capable of USB device mode, they all want to be USB host. in other bus systems like I2C this is called master-slave architecture
if you are lucky one of your PCs can be set to device mode and in this case this will work but your chances are very slim (because of the problem with the USB host and USB device mode)
https://unix.stackexchange.com/questions/195765/is-usb-to-usb-data-transfer-between-two-linux-oses-possible
a better solution would be to use ethernet
there are also modules in MATLAB for real-time communication over ethernet (Real-Time Transmit and Receive over Ethernet)
if your pcs have unused ethernet ports use an ethernet crossover cable (http://en.wikipedia.org/wiki/Ethernet_crossover_cable) and connect the pcs (i.e. http://www.ccm.net/faq/6340-connect-pcs-using-a-crossover-ethernet-cable)
else use an ethernet switch (or hub) to establish the ethernet communication between the pcs
beside MATLAB for communication you can use i.e. ssh or install a vnc server on one of the machines and remote-control it with a vnc client on the other,...
USB
with USB-to-ethernet adapters (ebay,...) you can use ethernet over usb when connecting the usb-to-ethernet adapters via a ethernet crossover cable
another possibility is to use two USB-to-serial adapters and connect them with a RS-232 crossover cable and then use RS-232 protocol for communication (putty,...)