Modbus TCP / multiple variables and data formats

This is very good Project! I started to work with this programm. As an begginer I cannot find two data formats that I need for my Modbus variables'definition:
— u64 — unsigned 64-bit (4 registers)
— s64 — signed 64-bit (4 registers)
How can I set this type of data?

Also I have another question. Can I define reading schema for reading of one device with multiple variables in text redactor or in excel and after this to import the parametrization data into the programm? Can I save parametrization and copy/paste for multiple devices?

Good luck with project!

Python and MODBUS

How can we use MODBUS variables within Python Scripts?
Also, Is there any manual that describes the Python commands that can be used in FreeScada?




I would like to create an «AnalogueTextValue» the will show the sum of four (4) MODBUS variables.
I have already tried to use the Simulation Settings and create a new variable_1, but I am not very familiar with the Python Syntax to do it correctly.
Can someone help me?


ModBus RTU

Hello All!

I am trying to find out, how do I change or modify a ModBus Register.
I want to create a button and this button should change a designated register which is responsible to switch ON/OFF a relay.
I am already manage to read a register, thanks to the example on the blog.
But I do not know how to change the values.
Thanks for the help and hints in advance.


Chart & database bugs in

I'm using FreeScada to visualize an RS-485 network of temperature controllers. For this I'm using the chart function and the SQLite database facilities.
1) I'm getting the data in and out allright but have some issues with the chart function: The hi/lo ranges are initially set to -1,1, but if you want to set them to 200,300 you get an error message that the lower value should be lower… If you then do -200,200 it works and also 0,300 works. Sometimes the designer mode accepts a range and the runtime will then not accept the resulting case.
2) In the SQLIte database I cannot change the 1000ms value, I change it, save it, but it still comes back 1000, even after leaving the program. (I'm getting the data in my database)
3) I had issues with the chart function running on a Dutch Windows XP; The hi/lo range came out as -1;1 iso -1,1. This could be a country setting issue, but then the problem as described in 1) still happens. You may want to check in your software whether you are installing it on a US/UK based Windows and otherwise exit in the setup fase.
4) You can't see which version one is using of freescada, you can check for updates but sometimes it says there is a new one which is not true.
Keep up the good work!

Connecting to MODBUS PLC

MODBUS Plugin Configuration and test


MODBUS is an application layer messaging protocol, positioned at level 7 of the OSI model, that provides client/server communication between devices connected on different types of buses or networks.
It is currently implemented using:
TCP/IP over Ethernet at a reserved system port 502 on the TCP/IP stack
Asynchronous serial transmission
MODBUS is a request/reply protocol and offers services specified by function codes. MODBUS function codes are elements of MODBUS request/reply PDUs.

( Read more )