I developing one j2me application for read value from power meter over modbus protocol serial communication. I have code here to read Holding register but m not getting response from meter.so.
Is there any Modbus library for j2me?
Help me please.
Thanks in advance.
A known and mature MODBUS commercial library for Windows and Linux is for example, SuperCom. A commercial software library that offers MODBUS for serial and TCP data communications and includes many MODBUS variations too. Client (Master) and Slave functionality also included. And it offers many samples for well known compilers (more).
There surely exist more commercial solutions there.
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Over the last couple of years I have been looking for an easy way to control a few relays from Javascript. I want to build a web App to control starting sequence horns for sailing races.
I recently discovered webUSB and it seems like exactly what I need. A direct connection from JS in chrome to the USB world. Simple coding in a language I already use.
On the hardware side I am having trouble finding a product that is compatible. Googling USB Relay finds 100's of products that all seem to rely on some proprietary SW for the OS. I can find lots of educational demo's that turn an LED on and off.
Does anyone have any ideas where to find such a product?
While I'm sure you will be able to find USB relays that can be controlled via WebUSB, most USB relays will probably come with some kind of serial port driver, e.g. https://numato.com/product/1-channel-usb-powered-relay-module uses a CDC serial port driver. These can be controlled using Web Serial, available in Chrome 77 and later behind a feature flag. For a tutorial, see https://codelabs.developers.google.com/codelabs/web-serial/
Explainer: https://github.com/WICG/serial/blob/gh-pages/EXPLAINER.md
API docs: https://wicg.github.io/serial/
If you search for "5V USB Relay Programmable Computer Control For Smart Home" on eBay, you will also find low-cost relays that use HID instead. The advantage of these is that you don't need any serial port or USB drivers, as it will use the operating system's built-in HID drivers. For that you can use WebHID. For more info, see https://github.com/robatwilliams/awesome-webhid.
i was developing some application in java on a pi. One part of of the application exchanges data via modbus tcp, therefore i must implement a modbus tcp slave.
There are further points, that make that situation a little bit difficult. The server should support different user ids and modbus register maps that should not be built of thousands of fake registers.
First i experimented with jamod, which is good for the master part of my modbus application, but has problems with different user ids and i didn't figure out how to create registers with specified addresses.
Now i realized that the modbus slave must not be part of my java application. I'm searching a stabile running, testet software for raspbian, which fulfills my requirements. I found very much testing software implemented in python, c and many other languages.
Can you give me some advise, which software could be a good solution for me.
I have very low knowledge about ModBus controllers, I have a Protocol3 Controller System http://www.despatch.com/protocol3.aspx that I want to control using a Python GUI.
I know that I can control the Protocol3 via ModBus. My Protocol3 has an ethernet port and I can talk with the controller using their software, however, controller software is very limited and I want to take full control using Python.
Does anyone have a clue of how the ModBus works? Do I have to buy an ModBus controller to set is as Master and set my Protocol3 as Slave?
Thanks in advance
I have find an article that help me out to understand and write a pice of software to control my Despatch Protocol-3 ModBus Module.
https://github.com/sourceperl/pyModbusTCP using Python Module "PyModBusTCP" http://pymodbustcp.readthedocs.io/en/latest/ and Protocol3 programming guide.
I think I can close now this topic.
Thanks all for stop by.
For my project I have an Android phone and an Arduino device that communicate via Bluetooth. I was wondering if anyone knows any software tools I could use to monitor a bluetooth communications between two devices. Something like a packet eavesdropping. Preferably for Linux.
Take a look at ubertooth one. In the linked webpage there are instructions on how to build the dongle, as well as links to shops selling assembled dongles may be bought. Ubertooth one should work well with Kismet, and thus in Linux, by using a BT plugin (disclaimer: I have no personal experience on this).
Sounds like you are after a Bluetooth sniffer.
Bad news: They are almost exclusively Windows OS based and cost mega-$.
http://www.fte.com/products/bluetooth.aspx
If you were using BlueZ for one side of the communication you could use the BlueZ HCIDUMP app and Wireshark.
I don't think anyone has made a Linuz/Bluez Sniffer - could be wrong.
I had planned to do mini project. With GPS modem using GPRS(sim card with internet connection) and i need to send the data from GPS modem to a website. Is it possible? If so how it can be done? What are the languages needed? And also tell me about the best GPS device?
GPS devices communicate using a standard protocol called the NMEA protocol.
Assuming you are using .NET you can check out the Positioning code in the DotSpatial open source project: http://dotspatial.codeplex.com/
They've got classes to decode the NMEA strings and can probably do much of what you are describing out of the box.
As for the best GPS device, if you need standard resolutions, any GPS device will do. They can be had for 10's of dollars. We often use the USGlobalSat model BU-353, although this is USB so it may not work in your application.
For what you want u must do 2 things
1. Create a TCP Listener which will wait for info using TCP in same port and put into database
2. Create a web or windows application for you read from database.
i have done something like this in my recent project.
Regards.