Sign in to follow this  
Followers 0
Andrei.s

Free, Powerful Modbus RTU/TCP Slave Simulator

9 posts in this topic

Posted (edited)

 

A new free Modbus RTU/TCP slave simulator tool - Unslave - has been released.

It is focused on simplicity, usability and ease of setup.

Instead of a GUI it supports flexible JSON-based configuration, where you setup slaves like this:

"slaves": {
    "1": {
        "isOnline": true,
        "registers": {
            "HR0": 1,
            "HR10": "0x0A",
            "C0": true,
            "C999": {exception: 3}
        }
    }
}

This type of configuration has great benefits - you can easily switch between different setups by specifying a different configuration file:

unslave.exe newConfig.json

You can put the configuration under source control and track changes.

Unslave lets you configure any number of slaves, setup values of every Modbus register, setup Modbus exceptions.


In addition, Unslave displays and write to a file the logs of all communications on the link. This is very useful for debugging:

2017/06/06 17:21:54.310 - TRACE: Byte received: 1. Total: 1
2017/06/06 17:21:54.310 - TRACE: Byte received: 3. Total: 2
2017/06/06 17:21:54.310 - TRACE: Byte received: 0. Total: 3
2017/06/06 17:21:54.326 - TRACE: Byte received: 60. Total: 4
2017/06/06 17:21:54.326 - TRACE: Byte received: 0. Total: 5
2017/06/06 17:21:54.326 - TRACE: Byte received: 1. Total: 6
2017/06/06 17:21:54.342 - TRACE: Byte received: 68. Total: 7
2017/06/06 17:21:54.358 - TRACE: Byte received: 6. Total: 8
2017/06/06 17:21:54.363 - INFO: Modbus frame received: [1 3 0 60 0 1 68 6]
2017/06/06 17:21:54.363 - INFO: Reading value: 1HR60 = 14119
2017/06/06 17:21:54.363 - INFO: Modbus frame sent: [1 3 2 55 39 238 110]

Updated Sep 17, 2017:

Since version 3.0 it's possible to update slave configuration at runtime via an HTTP API, for example:

PUT http://localhost:9000/slaves/1/registers/HR0

content-type: application/json

{
    "value": 1234
}

 

Edited by Andrei.s
Added more information

Share this post


Link to post
Share on other sites

Posted (edited)

Why would anyone pay for this product when numerous free MODBUS slave simulators exist?

From my viewpoint, editing a text file to change configuration is not "ease of setup".

 

 

Edited by Mark-

Share this post


Link to post
Share on other sites

Posted (edited)

14 hours ago, Mark- said:

Why would anyone pay for this product when numerous free MODBUS slave simulators exist?

This one if also free. It's literally the first word in the subject.

14 hours ago, Mark- said:

From my viewpoint, editing a text file to change configuration is not "ease of setup".

Well, text-based configuration is in fact preferable for many users, especially the programmer types. Some of the reasons are:

  • you can make huge changes quickly via copy/paste and search/replace
  • you can search and navigate large configs easily
  • compare different versions of the file
  • you can comment/document settings inline
  • to completely change the setup, you simply specify a different file
  • you can track changes via git or other source control solution
  • you can generate configuration programmatically

Those things are important for some users, including us, which is why we created this simulator and made it available for free

No software is fit for everyone, obviously. To many users a GUI is more familiar, and therefore easier to use.

 

Edited by Andrei.s

Share this post


Link to post
Share on other sites

Posted (edited)

1 hour ago, Andrei.s said:

This one if also free. It's literally the first word in the subject.

Yeah, I can read. It would not be the first post to be misleading on the web.

Clicking on the link has "pricing" right at the top of the page, the third word I see.

Selecting pricing has pricing for what appears to be a "slave simulator".

Next to it has "Community Edition". OK, that name is frequently used for free.

Click it and see this text:

"It's Free for Non-Commercial Use"

"20-Minute Session Limit"

"No Support"

Different ideas of "free".

OK, continue see "MODBUS Simulator", click on it and read "The Best Modbus RTU/TCP Slave Simulator". Wait really. Oh I see an unbiased opinion. :)

Now we are back to the starting page.

But wait again. So two products, both are MODBUS programs, both use the same "easy" text configuration, one acts as an HTTP server connecting to "slaves" and one is a slave simulator with only text display and both state free.

I see how there is no confusion.

 

Edited by Mark-

Share this post


Link to post
Share on other sites

Posted (edited)

 

On 6/13/2017 at 9:32 AM, Mark- said:

Yeah, I can read. It would not be the first post to be misleading on the web.

This one is not misleading though. The link delivers what is promised in the post title. I'm sorry you still feel it's misleading.

On 6/13/2017 at 9:32 AM, Mark- said:

I see how there is no confusion.

The link I provided leads directly to the page where you can download the said program for free. And it does not have any limits.
I'm sorry you got confused. You are right though, the web site does needs improvement.

In any case, the  slave simulator program (Unslave) is in fact completely free and can be downloaded without any hassle. I encourage people who are interested to try it out.

On 6/13/2017 at 9:32 AM, Mark- said:

Next to it has "Community Edition". OK, that name is frequently used for free.

This is for a different product. Its is an HTTP/REST API over Modbus, with tags, polling and other data acquisition features. The free version has limited session time. I have not mentioned that product in this thread.

On 6/13/2017 at 9:32 AM, Mark- said:

both use the same "easy" text configuration,

I have already addressed the text configuration issue earlier. Although it works really well for many people, we do have a modern cross-platform GUI and HMI builder in development for Unserver.

As for the simulator tool - we made it for ourselves because the alternatives didn't work for us (for the reasons I mentioned). We uploaded it in hope that it could be useful to others, free of charge. Enough developers have downloaded it, so I guess it was worth it. 

Unfortunately, quite often people on the internet feel the need to hate/criticize something just because they don't need it personally. 

Edited by Andrei.s

Share this post


Link to post
Share on other sites
6 hours ago, Andrei.s said:

You are right though, the web site does needs improvement.

Indeed.

Quote

Enough developers have downloaded it, so I guess it was worth it. 

Not a good metric for usefulness of a program.

Quote

Unfortunately, quite often people on the internet feel the need to hate/criticize something just because they don't need it personally. 

That is from left field and has nothing to do with my comments. (Seems to be a bit of projection.)

Share this post


Link to post
Share on other sites

Listen, guys.  You both sound like you are strutting peacocks.  Please take this to Private Message and then you go at it tooth and feathers...:disgust:

Share this post


Link to post
Share on other sites
10 hours ago, Jay Anthony said:

Listen, guys.  You both sound like you are strutting peacocks.  Please take this to Private Message and then you go at it tooth and feathers...:disgust:

All right, sorry about that.

Share this post


Link to post
Share on other sites

Hello everyone,

We want to make Unslave the perfect programmable Modbus simulator.
Since publishing, one of the most requested features has been the he ability to change the configuration "on the fly".

Today we are releasing Unslave 3.0 with a buit-in HTTP JSON API to support this use case.
The API is intuitive and just works. For example this request will update a register value:
 

PUT http://localhost:9000/slaves/1/registers/HR0

content-type: application/json

{
    "value": 1234
}

 

The tool is still completely free. You can learn more and downlod unslave here:  Modbus Slave Simulator

Please do get in touch if you have any feedback.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0