Simulation of an ASCII driver in Node-Red: Creation of a flow that generates random numbers

A warm welcome, I apologise in advance if the topic is not in the section it should be.

I have a problem with creating a working flow-a. Namely, I would like to "simulate" in node-red a driver that understands commands by ASCII and returns a response, e.g. I send in ASCII the symbol A<CR> , node-red returns me a string where the beginning is always the same and the last three positions are random numbers in the range 000-999. Example: device_1_14_11_197<CR> , another example: device_1_14_11_043<CR> .

I send a different symbol, e.g. B<CR> , node-red is supposed to reply: device_1_14_9347558130<CR> lub device_1_14_0003259735<CR>

As you can see, the second answer looks similar to the first, however, here there are more random numbers.

Node-red is running on an RPi4, I have communication via a usb-uart adapter. With the uart I am connected to the raspberry, the usb I have to the PC as a COM port, the preview and communication via COM I have through the Hercules program from HW group.

Could you please send some flow or somehow guide me on the subject?
Regards


_________EDIT

After a few hours of tedious work, reading the internet, I managed to partially solve the problem, however it is a half way solution, but does not satisfy me 100%



It's hard to explain what's going on with the whole program at the moment, but it's not working as I'd like. Overall it works poorly, maybe someone can take a look and tell me what is wrong? Generally now no matter what I type as a query node-red responds for both values/queries at the same time, even if I only type A or B as a query.... Is there anything that can be done about this, or throw it into a corner? Maybe my thinking is incorrect, maybe something needs to be done differently? I have no idea......

I just cut out the function block and inject and the programme seems to work fine.
Injecting A only answers A, injecting B only answers B.