Hello. I have very many years of C development experience, with much of that developing network enhancement, monitoring, and analysis software, all written in C (as well a bit in Visual Basic, and, lately, in Golang). My network analysis software projects in C include features to measure overall rate, and also rate by protocol (TCP, UDP, and others), in both bits per second and packets per second. I have never worked on MODBUS, true, but I am sure I can figure that detail quite quickly. In short, I'm your freelancer -- I will understand what you want done quickly (I just about know already), and I will know where to look and what to change in your existing code, written in a language with which I am intimately familiar. I am available immediately, and should be able to get this done for you in a day or less.
I am available to discuss the project at your earliest convenience.
I urge you to select me, you will be quite pleased. Thank you for reading my bid proposal.