Found this while searching! https://www.udemy.com/how-to-program-an-arduino-as-a-modbus-tcp-client-server/?utm_source=adwords-learn&utm_medium=udemyads&utm_campaign=NEW-AW-PROS-TECH-US-DSA-EN-ENG_.ci_.sl_ENG.vi_TECH.sd_All.la_EN.&utm_content=deal4584&utm_term=.ag_43090402494.ad_205975680648.de_c.dm_.pl_.ti_aud-299743148827:dsa-334302743449.li_9022658.pd_._&gclid=Cj0KCQiA-qDTBRD-ARIsAJ_10yK0VEnmUh0oCXtmEz3t3V2p5Mtl-jOih_YUJP_uSnvtZ_KLUffzf54aAil1EALw_wcB
I know it is a paid tutorial but it may be worth it if it works. (Arduino Modbus TCP Example)