Posts made by stepan.ozana

@Jan-Reitinger Nice. Just one small remark: There's no need to use a two-dimensional input here—even formally. You can define a system with a one-dimensional input, a certain number of states, and possibly a different number of outputs. Instead of using u(t)=[sin(2πt);0] you can simply write u=u1=sin(2πt).

@Jan-Reitinger I suggest having both "reference model" suffering from noises and "reference exact model" for comparison of EKF efficiency and performance.
Please take a look at my suggestions and let me know your opinion. It seems to work. Maybe it needs a bit tuning in terms of Q,R, versus noise generators. Also, I am fighting with alignment of free text within boxes.
Here is my update:
linear-system_v2.zip

@Jan-Reitinger Sure! I'm glad to have contributed to the collection of examples. Regarding the timing issue, I may have used the wrong terminology. I don’t observe 'Overtime' in the Task Diagnostics, but I do see 'CoreWarning GTimer: Period overtime.' in the System log.

This issue occurs in the original 'EKF.zip' mentioned at the beginning of this thread—at least on my PC. It may function correctly on other machines. It may be due to using Windows instead of Linux. I will tes it on Linux.

Here is the screenshot:

Moreover:
I just realized that the current version of the example is not fully correct because it lacks process noise and measurement noise. It seems that process noise should be implemented within the block currently referred to as the 'Reference Exact Model,' which would no longer be 'exact.' Measurement noise can be simply introduced as an added signal to the model's output.

I will try to incorporate these modifications in the next few days. I plan to create a 'Reference Model' that mimics the real process while accounting for both types of noise. Once I have refined the example to meet my expectations, I will get back to you.

@Jan-Reitinger I upgraded your example. Now it uses exact reference model both for verification and emulating output measurements to be used as input to the estimator.

However, there is some timing issue here. I use tick=0.02, ntick0=4. It means period of the task is 80 ms. If I go lower with that, I receive overtime in diagnostics. This is odd, because it means that computational load is too high.
It should be much less than that.
Here is my current version:
EKF_John.zip

@stepan-ozana Regarding "Update - second part of the problem": In the meantime, I conducted a simple test of my idea using CallExt(".Taskname.blockname"), and it seems to work. If anyone is interested, I can share the test results here.

.test_on_demand_running.zip

Update - second part of the problem : I am also wondering if slower task can be run "on-demand" - asynchrounously, from the faster task. Is there any similar mechanism like for the general blocks inside some tasks that can be halted (marked as red-crossed blocks) and run at specific times using REXLANG with CallExt(".blockname"). Or is it possible to use the entire connection string in CallExt? Such as
CallExt(".Taskname.blockname")?

Hi,

I’m wondering if there’s a way to exchange data asynchronously between tasks. Specifically, I have two tasks: one running faster and another running significantly slower. The slower task performs a computational process that varies in execution time within known rough limits, which is why I’ve set its period slightly oversized.

My goal is to pass the results from the slower task back to the faster task as soon as the computation is complete, rather than waiting for the next cycle of the slower task.

Is there a recommended approach for achieving this?

Thanks,
Stepan

@stepan-ozana Little update: Under Linux, using RPi, it behaves much better. BUSY signal stays ON for 2 task periods.

Hi, I have a question related to the EPC block.
Let's suppose I have an external program to be called and executed by EPC block. I used example "\0202-11_EPC_Generic_Linux_Script" , made some modifications and made it run under windows, using epc_script.bat where windows syntax is given to run particular external program (*.EXE file).
I was wondering how much time is spent on execution so I concentrated on analysis of BUSY output of EPC block.
It seems like BUSY signal is ON for quite a long time.
Then I made a special extreme variant where epc_script.bat is completely empty so that it does not do anything when launched.
In my executive I used tick=0.01, ntick0=2. However, BUSY signal stays ON for 250-300 miliseconds each time EPC runs the script which does nothing (also, ifns and ofns are empty).
Is it OK? Which activities occure during this time?

@Jan-Reitinger I share my solution if anyone is interested. It shows writing and reading uint16 and double values over the Modbus TcpIP between some REXYGEN target hosting the Modbus server on the client (slave) side and Matlab running on PC.
example_ModbusTcpIP_Comm_RpiToPC.zip

@Jan-Reitinger UPDATE:
Now I'm able to read and write uint16 numbers, and I will focus on doubles.
I still have some doubts about this solution, for example where the modbus server is actually running or by which machine is the modbus server created (Matlab's modbus command seems to connect somee server and not to create any, and RPi hosts the slave part).

@Jan-Reitinger Thanks for your assistance. I confirm that this modified script works fine.

@Jan-Reitinger Thanks for your assistance. Having followed your advice
m = modbus('tcpip', '192.168.111.2',502)
I get the following result:
m =Modbus TCPIP with properties:
DeviceAddress: '192.168.111.2'
Port: 502
Status: 'Connected'
I will now focus on how to read and write the data, because so far I have no success after playing with this for two hours.

It seems that my bad was using RPi as master instead of slave.
However, there are two things that made me confused and did not ring a bell in order to make me try to switch the roles:
-documentation for the modbus command does not explicitely declares if it creates master or slave, it says it "constructs a Modbus object"
-moreover, the documentation of the modbus function declares that when using
m = modbus(Transport,DeviceAddress)
"DeviceAddress is the IP address or host name of the Modbus server"

If it's not a mistake, it's very confusing then.

Hi,
I have a question related to example
\0402_Modbus_TCP\0402-04_Modbus_TCP_PID_Loop
I want to communicate between Rpi and PC, while Rpi will represent the master and PC will serve as the slave.
If I run your example as it is, everything works just fine. THe master part goes to Rpi and slave part to PC, both using REXYGEN.
However, I need to create some testing utility that would use the master part as it is, but the client would be implemented in some other environment than REXYGEN. I downloaded master part to Rpi and then used the following syntax in Matlab:
m = modbus('tcpip', '192.168.111.2', 1,502)
I double checked all IP addresses and ports. I get the below mentioned error. It's the same if I use Python or some external dedicated utility to analyze modbus communication.
Does the slave part in your example do anything special? What else should I check to be able to establish the connection?
Thanks, Stepan

m = modbus('tcpip', '192.168.111.2', 1,502)
Error using modbus (line 96)
Requested transport resource is either in use or does not exist. Cannot create a communication link with the remote server. Please check the input arguments(ADDRESS and PORT) and make sure the server is running. Additional Information: Pokus o připojení selhal, protože připojená strana v časovém intervalu řádně neodpověděla, nebo vytvořené připojení selhalo, protože neodpověděl připojený hostitel.

@stepan-ozana It seems like it behaves the same even if I set some password for admin user. Can you please double check if this example works for you?

Hi,
I have a question related to example \0302_IoT_Integrations\0302-03_REST_API_Python_Bash_etc
and Matlab REST API communication.
If I run this example with the default admin credentials
(admin and empty password), using
options.Password = ''; in getdata.m ,
I get the following error:

The content reader issued the error message: "Unable to parse the JSON data while reading the content downloaded from URL 'http://127.0.0.1:8008/login?u=api/login'
I think it reads the html content of the initial webpage and it does not overcome the issue related to the empty password.

I can of course set some non-empty password, or I can implement some workaround such as setting
auth.enabled=0 in rexcore.cfg.

But still I'd like to ask if there's a way how to run this example
with blank password without modifying rexcore.cfg.
Thanks, Stepan

@cechurat Thanks for info. As my model of the plant is created in external program in the form of FMU, I found that I could run fast parallel simulations in order to compute my cost function over future prediction horizon using https://github.com/CATIA-Systems/FMPy which can be called from the PYTHON block within the REXYGEN project

Hi, I wonder if it's possible to call some standard REXYGEN block from python code embedded inside PYTHON block.
Let's say I use PYTHON block and its main() function needs to solve some optimization task using python solver for predicitive control . To do so, I need to compute cost function, therefore I need to call parallel simulations to predict the states over some prediction horizon. Currently I can run such parallel simulation (time-scaled, faster) using REXLANG and its CallExt functions such as CallExt(".STATESAVE"), CallExt(".STATELOAD"); and CallExt(".SubModel") inside FOR loop inside main(void) of the REXLANG. Now I'd like to create similar solution using python code but I see no way how to call REXYGEN blocks from python. Any help appreciated. Thanks Stepan

@Jan-Reitinger Thank you so much for efficient help. Now it works exactly as I wish.

@Jan-Reitinger Thank you so much for efficient help. So far I have used Inport and Outport blocks for working with subsystems. Now I am able to use them to exchange data between tasks.