Ok I finally figured it out. I really didn't think it would be an issue, but I was wrong. So my network card has wifi and ethernet. I disabled my wifi entirely and ran the program, it works perfectly now. The whole time Advanced HMI has either been looking for the ML1100 over wifi, or the wifi connection was preventing it from connecting through ethernet. Either way, disabling wifi solved the problem! Thanks to everyone who has tried to help me along the way! (ALSO, I did end up using the EthernetIPforSLCMicroCom driver, and rslinx can be active while running advanced HMI. I assume you were correct in that it only needs to be off when connecting through a serial port) Thanks again!