Companion failing to manipulate serial data. Need it to pull two characters from string, convert them from hex to integer, and assign integer to variable.

[chaoticnewt]

Make sure you're on the latest stable or beta build

• I have tested this on the latest stable or beta release

Is this a bug in companion itself or a module?

• I believe this to be a bug in companion and not a specific module

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I am trying to parse incoming serial data to extract the current volume level and display the value on a streamdeck with a raspberry pi. I want to display the current volume level integer on a button of the stream deck.

I have a trigger monitoring the serial responses coming in from an iTach IP2SL (named SL3-02). I have done much troubleshooting. The trigger will assign a text or value to the integer, so long as I do not try to manipulate the incoming string.

Here is my original attempt, input into the value field in expression mode:

includes($(SL3-02:response), "4112") ? parseInt(substr($(SL3-02:response), includes($(SL3-02:response), "4112") + 4, 2), 16) : $(custom:display_vol55)

Subsequent tests that also fail:

(slice($(SL3-02:response), 12, 14), 16)
parseInt(slice($(SL3-02:response), 12, 14), 16)
parseInt(slice($(SL3-02:response).toString(), 12, 14), 16)
parseInt($(SL3-02:response).split("4112")[1].slice(0,2), 16)
parseInt($(SL3-02:response)[12].toString() + $(SL3-02:response)[13].toString(), 16)
parseInt(slice(String($(SL3-02:response)), indexOf(String($(SL3-02:response)), "4112") + 4, indexOf(String($(SL3-02:response)), "4112") + 6), 16)
substr(String($(SL3-02:response)), indexOf(String($(SL3-02:response)), "4112") + 4, 2)
parseInt(regEx($(SL3-02:response), /4112([0-9a-fA-F]{2})/, 1), 16)

I also tried forcing lower case, no change.

When I ran ' includes($(SL3-02:response), "4112") ? "FOUND_IT" : "NOT_FOUND" ', my custom variable printed "FOUND_IT" which makes me think the issues lies with the actual parsing and/or hex conversion.

Serial response is printed in the variable because I had $(SL3-02:response) in the value field.

Maybe I am missing something, maybe this is a bug.

Thank you for your time.

Steps To Reproduce

1. Create custom variable (ie 'display_vol')
2. Create trigger.
3. Add event to trigger: 'On variable change.' My 'variable to watch' is my iTach serial device connection (so SL3-02:response)
4. Add action: 'internal: Custom Variable: Set value' and set 'Custom variable' to 'display_vol'
5. Put 'Value' into expression mode, then try to parse the response string with string manipulation and hex conversion.

Expected Behavior

I expect it to pull characters 12 & 13 from my serial response string (for example, aaff000341124da2). In this string the characters are '4' and 'd'. Then run a hex conversion on 4d to convert it to its integer value, here it would be 77 (current display volume). My end goal is just to print the variable value on a button so they can see the current volume on the stream deck.

Environment (please complete the following information)

- OS: Windows 10
- Browser: Chrome 144.0.7559.59
- Companion Version: v4.3.0+8950

Additional context

Display in question is a Samsung QM55C. I am changing button feedbacks based on power responses with success, but that doesn't require string manipulation.

includes($(SL3-02:response), "411101") ? 1 : $(custom:display_power55)
includes($(SL3-02:response), "411100") ? 0 : $(custom:display_power55)
if 1 then power is on
if 0 then power is off

[chaoticnewt]

Additional notes:
iTach Module v2.0.0
'indexOf' successfully returned 8, but slice or substr failed to return the characters at the offset. Perhaps a potential hidden character/null terminator issue in how the module stores the string buffer.

[Julusian]

To make this easier for yourself to debug, I would suggest trying to break your expression over multiple lines, and testing it as an expression variable. The last line is what the result will be, so the combination of these makes it really easy to comment lines out and get a live updated value changing as you edit.

Here is my original attempt, input into the value field in expression mode:

Starting with this, in our expression syntax parseInt is not a valid function. You want fromRadix. And includes returns a boolean (as you find later, indexOf is what you want here.

Subsequent tests that also fail:

The following are also not valid functions: String, regEx, .toString()

All of the supported functions are documented: https://companion.free/user-guide/beta/expressions/functions (or the user guide link within companion)

As documented there, substr is substr(val, indexStart, indexEnd). You appear to be trying to give a length instead of an end value, which will result in it returning an empty string.

An expression that I think will work for you (it seems to from as close to the same input string):

index = indexOf($(SL3-02:response), "4112")

index == -1 ? $(custom:display_vol55) : fromRadix(substr($(SL3-02:response), index + 4, index + 6), 16)

And based on that you are using a trigger to set a custom variable whenever a different custom variable changes; Perhaps it would be easier to write this as an expression variable?