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,...)
Related
Is it possible to connect the Ethernet port (of a Raspberry Pi) directly to a Modbus TCP RJ45 port (such that the devices can talk to each other)? Or is this not possible without a converter?
I am unsure if this is the correct forum, but I believe this should not be specific to the Raspberry pi.
Short answer - Yes... But....
As per the comments this is possible but there are a few things you will need to do (i.e. some configuration will be needed).
I think it's worth nothing that "Modbus TCP RJ45 port" is not really a meaningful term. Modbus is an application layer protocol; this depends upon a number of underlying layers:
Transport layer - TCP
Network layer - IP
Datalink Layer - Ethernet
Physical Layer - Ethernet cable with RJ45 connectors
You don't need to understand this in detail; the point is that before ModbusTCP will work you need to have a working TCP network (which all Modbus-TCP devices will support; generally via an RJ45 Ethernet connection). As such a better question probably is "If I run a CAT-5 cable between a Raspberry Pi and another device (Modbus TCP unit) will I be able to connect via TCP?" (a lot more people know about TCP/IP networking than Modbus!).
The first thing to consider is Ethernet. Running a cable directly between two older devices will often not work because they needed a crossover cable. Almost all modern equipment (including the Pi) supports Auto MDI-X which means the cable will just work. You can also connect the units via a switch (and doing this removes the need for Auto MDI-X).
Next you need to consider the IP layer. When you connect your Pi to your home network it will (usually!) be given an IP address by a DHCP service (usually running on your router). If you are connecting the Pi directly to the device then there will be no DHCP service so you will need to manually assign IP addresses to the devices (and ensure the subnet is correctly configured). A common way to check if an IP connection is working is to use the ping command.
With the lower layers working ModbusTCP will generally 'just work'. Many ModbusTCP devices also offer a browser based configuration and checking that you can access that is a good way to confirm that the network link is working.
One further question is probably "should I do this"; it's OK to hook things up this way to make some quick changes. However generally you will want the Pi to access other network resources so connecting everything to a router (home router will work; for remote devices a cell router is often used). You can either give the Modbus unit a static IP manually or use the routers configuration pages to assign it a static DHCP lease (otherwise it's IP might change from time to time).
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 bought a new Arduino Ethernet Shield and hooked it to the Arduino Uno.
I am trying to set the IP address of the device to 192.168.1.177 tried File-> Examples -> Ethernet-> Webserver.
When I upload this - I get a "server is a 0.0.0.0'message in serial monitor !
My IP is set to 192.168.1.177 and setup a mac address of 0xB8, 0x27, 0xEB, 0x98, 0x46, 0x61 in the webserver code.
Appreciate any help in setting this IP address. ( I tried other combinations as well )
The Arduino Ethernet shield is mounted on the Arduino Uno, and connections are lined up .
i fix this problem by pressing firmly the shield to the board
This can manifest from many different causes. I ran into this and figured out that in my case, my the USB port + cable were not allowing sufficient power to the Ethernet chip.
I have 3 cables, 6in, 3ft, and 6ft. Only the 6" one had sufficiently low voltage drop to power the shield.
I honestly couldn't believe it, but there was a 0.1V drop between the 6in and the 6ft cables. When plugged into A USB 3.0 port with the Arduino loaded, I measured ~4.5V for the working 6in cable vs ~4.4V for the non-working 6ft cable.
I have 3 types of USB ports: 1.1, 2.0, and 3.0. Only the USB 3.0 ports provided enough power to power the shield. Thus for my case, I had to use the shortest USB cable on the 3.0 port.
When the Arduino's 5V rail was sufficiently sagging, the 3.3 Linear Regulator entered dropout mode and on all the non-working configurations I saw ~3.1V on the Ethernet shield's 3.3V rail, which is apparently sufficient to cause this symptom.
My serviced office provides internet via a single ethernet cable (internet via lan). I wish to share this to multiple devices both wirelessly and over ethernet.
The office has given me specific IP, subnet, primary+secondary DNS details to access the internet over the ethernet cable.
What type of device do I need so that I can share this ethernet-internet connection to my own devices?
Just a simple router with wireless capabilities, no?
I want to monitor the HTTP traffic sent/received from my iPhone. The iphone is connected to the Internet via my wifi router.
I want to capture packets from my windows 7 station.
Thanks for your help.
You have a few options here:
If your wireless router has a port mirroring or port spanning feature, turn it on and point it at your workstation's IP. Use Wireshark on your workstation to look at the packets arriving on the interface assigned to that IP.
If your workstation has a wireless card, get Connectify for Windows 7 (turns wireless card into Wifi Hotspot). Connect iPhone through Windows 7 wireless, and workstation through ethernet to the internet. Your workstation will effectively act as a router for your iPhone and you will be able to record iPhone's packets passing through it.
Get an ethernet hub (make sure it is not a switch, you won't see all packets on every interface with a switch), and connect your workstation, wifi router and internet to it.
Get a switch with port mirroring feature, configure port mirroring to forward a copy of all packets to your workstation.
Another option that I wish someone would have mentioned to me is pfSense. This is an operating system based on BSD made to serve as a firewall. Top of the line routers have, say 400 Mhz of processing speed, and unimpressive amounts of ram. The lowest-end computer you'll find these days has better specs than that, and of course, it's upgradeable. You don't have to bother with those terrible Cisco licenses (no DHCP with no license, 20 DHCP users at one license level, 100 users at an higher lever? Ludicrous), etc. Best of all, you have "root' access to the system, so you can run whatever you want on it (including wireshark, say)!!
Make sure you have two sufficiently fast ethernet cards. You'll set your wireless router to not do NAT (because pfSense will be doing that), then you can get to work setting up your VPN server, etc. without thinking about cisco licensing, etc.