Node Red - Modbus Custom FC

General
1

Hello all,

I am currently working on a project in which I need to read a specific device via Modbus in Node-RED. The problem is that this device uses a custom function code (FC66), and unfortunately in Node-RED I immediately get the error message:

“FC Not Valid”.

I am familiar with the standard Modbus function codes (such as FC1, FC3, FC4, etc.) and have managed to implement them in previous projects without any problems. However, the required FC66 is apparently not supported by the Modbus Flex Getter node in Node-RED.

My questions:

Does anyone have experience using non-standard function codes in Node-RED?
Is there any way to configure or modify the Modbus Flex Getter to support custom function codes?
Are there alternative nodes, libraries or methods to solve this problem?
I have already checked my device's documentation, and FC66 is required to retrieve specific data. It seems that this function code is outside the standard set, but I hope someone has experience with this and can point me in the right direction.

Thanks in advance for your help!

Edit/additional information:
I use modbus RTU

2

I don't think any of the modbus nodes are developed to support custom function codes.

I have previously done a POC, custom parsing that could be modified to use the serial nodes and support any FC - it is after all just simple ASCII codes and checksums.